The Future of Naval Aviation - ETH Z · Naval Aviation must also ensure that its forces have the...

MIT Security Studies Program

Naval AviationThe Future of


Owen R. Cote Jr.Associate Director

M.I.T. Security Studies Program

This report is a product of the M.I.T. Security StudiesProgram. It is the sixth in a series authored by Owen Coteand devoted to the subject of the U.S. Navy in the futuresecurity environment.

This series of reports is dedicated to the late Vice AdmiralLevering Smith, U.S.N., the technical director of the Navy’sfleet ballistic missile program during the development ofPolaris, and from 1965 to 1977, its director.

The author would like to thank Admiral John Nathman,Vice Admiral Mark Fitzgerald, Rear Admiral Thomas Kilcline,and Malcolm Taylor for their support for this project,and Jeanne Abboud and Harlene Miller for their help inproducing this report. It, along with other MIT/SSP reports,is available at http://web.mit.edu/ssp/


When concentrated, multiple carriers are now able to produce effects ashore that would formerly have required many more

wings of tactical aircraft operating from local bases in the region, while at the same time protecting the sea base and

extending that shield ashore.

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Executive Summary

TODAY, ALONGSIDE ITS ALL IMPORTANT OPERATIONS in direct support of the GlobalWar on Terror, naval aviation also continues its now 60 year commitment to shap-ing the maritime and littoral environment through persistent forward presence. In

the longer term,naval aviation is also adapting to a series of geopolitical revolutions whichwill dramatically increase the future demand for a secure sea base capable of projectingdominant power ashore in wartime against the full spectrum of possible opponents. It isadapting to these demands by exploiting technologies and operational practices developedin the last decade that will greatly increase its ability to surge and concentrate forces rapid-ly; protect the sea base from new air, surface, and undersea threats; and find, identify, locate,track, and strike mobile as well as fixed targets ashore, under all weather conditions, andin timely enough fashion to produce the desired effects.

Formal Alliances Provide Predictable Access, Informal Coalitions Do Not

The main source of new demands on naval aviation is the decline in secure and pre-dictable access to overseas bases resulting from the shift in strategic focus away from thecentral front of Europe to the long Eurasian littoral, which extends from theMediterranean to the Yellow Sea. Along this arc, the United States lacks and is unlikelyto recreate the tight, long term alliance relationships which were a hallmark of the ColdWar, from which flowed assured access to bases ashore. Instead, it faces a security envi-ronment in which ad hoc coalitions will form to solve specific problems; access to basesashore will be episodic and unpredictable in advance of conflict, as was the case withTurkey in the run up to Iraqi Freedom; and the freedom to operate from such bases dur-ing conflicts can be suddenly withdrawn, as happened more recently in Uzbekistan.

Distributed Ground Forces Require Persistent, Distributed Air Support

Today’s ground forces, operating in dispersed fashion, far from sustaining bases, inextremely austere environments, and in units ranging from section to brigade — rely onair forces for combat power more than they did during the Cold War. In particular, theydepend on air forces for timely attacks against targets that emerge quickly and unpre-dictably in meeting engagements, and which must also be destroyed quickly.They alsodepend on air forces to detect, identify, and destroy larger concentrations of enemy forcesmoving to contact with elements of the distributed ground force. A sea base allows a sup-porting air force to operate in distributed and persistent fashion, while retaining the abil-ity to concentrate quickly and bring dominant power to bear.

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The Sea Shield Must BeDominant If the Sea Base Is To Be Effective

In order for the sea base to play a central rolein support of engaged forces ashore, it mustbe provided a dominant defensive shield, andmust be able to project that shield ashore. Ashield for the sea base preserves the accessnecessary for expeditionary maneuver war-fare against both existing and emerging mil-itary threats. When anti-access threats arepresent, the sea base will need to be able toplay offense and defense at the same time,and do so with absolute reliability, evenwhen anti-access threats appear relativelylow, and the temptation to trade sea shieldcapabilities for more sea strike will exist.

Adapting

Naval aviation is adapting to the demands ofthe new security environment across all itsmission areas and against the full spectrum ofthreats. At the most aggregate level, navalaviation is developing a force structure andoperating tempo which maximizes its con-tribution across the spectrum of conflict,whether measured in terms of time or threatlevel. In terms of time, this involves presenceand shaping operations in peacetime, crisisresponse operations designed either to deterconflict or to maximize early arriving com-bat power should deterrence fail, and largescale surge operations whose purpose is thedominant application of sea-based powerprojection with an eye to the rapid and deci-sive defeat of the opponent. In terms ofthreat level, this involves the developmentand insertion of rapidly evolving technolo-gies into sensors, weapons, and networks.The platforms which deploy these technolo-gies will be capable of concentrating todominate and defeat the high end threats,while also remaining prepared to operate

multiple smaller force packages in dispersedfashion that retain robust shield and strikecapabilities for use against more commonmid- and low-level threats.

The Spectrum From Presenceto Major Combat

For many years, the primary metric forassessing Naval Aviation capabilities hasalternated between peacetime presence andwartime surge requirements. In the lastdecade, carrier forces have operated simulta-neously along the entire spectrum frompeacetime to major war. For example, since1990, Naval Aviation has maintained a nearcontinuous 1.0 presence in the Arabian Gulf,along with a forward-deployed carrier inJapan and a frequent presence in theMediterranean. From this peacetime posturea forward deployed carrier has often beenflexed in response to crises in places like theArabian Gulf and the Balkans, trading pres-ence in one theater for another. In othercases, pairs of carriers have been concentrat-ed, as occurred off Taiwan for one month in1996, and in the Indian Ocean for sevenmonths in 1997-98. During both OperationEnduring Freedom (OEF) and OperationIraqi freedom (OIF), as many as six carriersat one time were deployed to support com-bat operations, and as many as eight totalcarriers were employed over the course ofthe conflict.

Metrics based only on peacetime pres-ence or wartime surge requirements fail tocapture the complex requirements generatedby a world in which presence, crisis response,and major surges are all necessary – some-times simultaneously.This makes force plan-ning more difficult, because the plannercannot focus on a single metric, such asneeding five carriers to maintain one in theIndian Ocean, or twelve to be able to surge

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eight. As it is more realistic to assume NavalAviation will be asked to provide all threefunctions, as well as others not yet imagined,a carrier force that is able to sustain thatmore complex burden is needed.

The force that is providing presence orconducting the Global War on Terror todaywill often be the first to arrive in a crisisresponse or major combat scenario tomor-row. Combat power applied in the first daysof a crisis response or major combat scenariois like the “golden hour” in combat medi-cine, because it produces relatively moredeterrent or warfighting effect than a largeramount of combat power that arrives later.The Navy has historically avoided tailoringits deployed forces to the lower threat envi-ronment in which they often find them-selves operating; instead, it deploys forcesthat are prepared for the full spectrum ofcombat. For example, when Iraq invadedKuwait in August 1990, the Independence(CV-62) battle group was in the IndianOcean, ready to respond, as was theEnterprise (CVN-65) battle group followingthe 11 September 2001 terrorist attacks onAmerican soil.

Technology and the Spectrumof Threat

Naval Aviation must also ensure that its forceshave the capabilities needed against the fullspectrum of threats.This is a more technolog-ically intensive process than force planning,and it has been the object of a decade-longNaval Aviation recapitalization strategy that isabout to reach fruition. Advanced airborneearly warning (AEW) aircraft; increased per-sistence and range for strike fighters; modern-ized airborne electronic attack (AEA)platforms; advanced surface, undersea, andmine warfare helicopters; and long range, per-sistent, land-based maritime patrol reconnais-

sance aircraft (MPRA) have been the majorplatform-related aspects of the carrier aviationmodernization strategy.

The Value of Robust AEW

Any advanced, integrated air defense systemrelies on a fleet of airborne early warning(AEW) aircraft with powerful radars provid-ing a persistent, high altitude view of thebattlespace. Only upon this base can an outerarea defense be erected that aspires to keepattackers well outside range of their targets,so they can be killed before they can launchtheir weapons. Without AEW, defenderscede enormous amounts of battlespace totheir attackers, decrease warning time, elim-inate multiple kill opportunities, and placeprimary reliance on difficult, close in, timecritical engagements against arrows ratherthan archers. If one looks around the worldon land, one can identify those few countriesthat actually seek to keep opponents out oftheir air space by their AEW aircraft.At sea,the presence or absence of carrier-basedAEW is even more decisive. Airborne earlywarning also determines the ability of thesea base to project power ashore in the faceof all but the most minimal anti-accessthreats.Thus, it is one of the main determi-nants of whether a sea base can play offenseand defense at the same time.

No Substitute For Range inCarrier Aviation

The long range, sea-based strike fighter, withits ability to engage in multiple, simultane-ous, and dispersed engagements 24 hours aday, is a key enabler of power projectionashore. Both OEF and OIF have proven theinestimable value of sea-based strike fightersas a distributed, timely source of fires overthe battlefield, both against fleeting high

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value targets, and in support of blue groundforces operating in dispersed fashion onnon-linear battlefields. Adding range totoday’s relatively short-legged naval strikefighters through enhanced organic missiontanking and greater internal fuel capacity canexpand the maneuver space of the sea basewithout compromising the reach or persis-tence of its main striking arm; increase theoverland persistence and coverage of thatstriking arm from the same maneuver space;or some combination of the two.The greaterthe range extension, the more flexibility andcapability result, allowing the commander atsea to maneuver and operate his sea base insuch a way as to task-optimize his forcealong the full spectrum of conflict.

The Need for AEA Is Not Going Away

Airborne electronic attack (AEA) is a keyenabler of strike operations by non-stealthyaircraft against even modest air defenses, andis central to any concept of air operationsagainst more advanced air defenses. Althoughthis is one of several possible future roles forUCAV, an AEA platform based on a longrange strike fighter is necessary in the midterm.The range and persistence of AEA plat-forms must be equal or even better than thestrike fighters they support.

Land-Based Maritime PatrolAircraft

Long range, persistent, land-based maritimepatrol aircraft provide the only way for adominant naval power to maintain a contin-uous presence and surveillance throughoutthe vast ocean and littoral spaces over whichit must exercise control. They often providethe most timely means of response, whetherto a fleeting undersea acoustic contact, a

report of a suspicious merchant ship, or animportant signals intelligence collectionopportunity. The maritime patrol fleet isevolving into a triad of more capable assets—the P-8A Multimission Maritime Aircraft,the Aerial Common Sensor, and the BroadArea Maritime Surveillance UnmannedAerial Vehicle—that are an important ele-ment in Naval Aviation’s recapitalization.Deployed in small expeditionary contingentsat the strategic approaches to and operatinglocations along the Mediterranean-Indo-Pacific arc, the new maritime patrol triadwill provide improved surface surveillance,antisubmarine warfare, antisurface warfare,and multisource intelligence collection.

Multimission Helicopters

Maritime patrol assets need to be comple-mented by a more distributed force capableof quickly responding to its cues; identifyingpotential contacts as friend, foe, or neutral;and either tracking the contacts or destroy-ing them, depending on the circumstances.The specific sensors, and weapons used toacquire and prosecute contacts in surfacewarfare, undersea warfare, and organic minewarfare missions will vary, but because theywill often be deployed and operated fromthe same platforms and in the same littoralbattlespace, there is a tremendous premiumon combining them on the same multimis-sion helicopter when possible.

New Capabilities andChallenges

New sensors, networks, and weapons, alongwith new platforms, will introduce someradically new capabilities for naval aviation.For example, there are already emergingtechnologies that will enable through theweather attacks against mobile ground tar-

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gets.There are also areas where the technol-ogy is less mature and where naval aviationfaces significant challenges, such as in under-sea warfare.

Eliminating the WeatherSanctuary for Mobile Targets

Radars suffer little or no interference fromweather but, unlike in air-to-air combat, ithas proven impossible to this point to useair-launched, radar-guided weapons againstcombat vehicles on the ground beyondranges of five kilometers or so. That con-straint has preserved a sanctuary from airattack for mobile targets when clouds liebetween the attacker and the target, becauseother means of attacking mobile targets havehistorically relied on visual acquisition of thetarget. GPS-guided weapons solve this prob-lem when the target’s location is preciselyknown, but the vehicles which comprise anopposing ground force often move frequent-ly and in unpredictable fashion, and combataircraft do not currently have the ability totarget GPS-guided weapons in real time.

In the near to mid term, strike fighterswill become capable of targeting mobile tar-gets temporarily at rest because the aircraft’sown synthetic aperture radar processing willsoon be capable of comparing an organical-ly-generated SAR image with an onboarddatabase of geo-registered SAR imageryautomatically and in real time. Alternatively,toward the same end, it will soon be possibleto use an organically generated SAR imageas a scene-matching template for a weaponwith an infrared terminal seeker, achievingthe same goal of targeting through weather amobile target temporarily at rest, while inthis case, also reducing or eliminatingreliance on GPS.

In the mid to longer term, one of severalpossible approaches to the all weather attack

of targets that are actually moving will also bedeveloped and deployed. One option will beto use bilateration or trilateration in a net-work of airborne radars to reduce the errorsin azimuth intrinsic to single radars whenthey are tracking moving targets, and to use adata link to give a weapon in flight constantupdates of the moving target’s changing posi-tion. Another option will be to improve ter-minal seekers on weapons to the point wherethey can acquire, recognize, and home on amoving vehicle after the less accurate cueingprovided by a single tracking radar.

Certainly, substantial limits will remain onwhat ground targets can be detected, identi-fied, and attacked from the air, but with theweather sanctuary for combat vehicles great-ly reduced, an opponent’s freedom to con-centrate and maneuver will also be greatlyreduced, enabling the distributed, non-linearapproach to battle that U.S. ground forceswill increasingly adopt.

Providing a Dominant Defenseof the Sea Base

In strike operations ashore, naval aviationwill often be part of a joint team, but whendefending the sea base from attack, the Navywill often be on its own.This is not a prob-lem in much of the world because mostcountries have no capability to projectpower out to sea. Of those countries of con-cern that pose a threat to the sea base, manydo so only with ground or small boat-launched, anti-ship missiles and mines, limit-ing both their reach and their effectiveness.Some more capable potential adversaries addmissiles launched by aircraft or major surfacecombatants and non-nuclear submarinesdeploying mines, torpedoes, and, in a fewcases, antiship missiles. At the highest end ofthe spectrum, the sea base may face an oppo-nent with over-the-horizon sea surveillance

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capabilities extending as far as 1000 miles forcueing antiship attacks by long range, termi-nally-guided, ballistic missiles and/or non-nuclear submarines with air independentpropulsion (AIP).

Though formidable compared to thenorm in today’s world, these potential anti-access threats do not equal those the Navyfaced down during the Cold War. On theother hand, because the Navy will be askedto play a much larger power projection rolerelative to land-based forces than was thecase during the Cold War, the Navy’s seashield capabilities must dominate the highend anti-access threat. The path to domi-nance in this mission area varies between theair, surface, and sub-surface environment,and the consequences for naval aviation varyas well.

Shoot Archers Not Arrows

On the surface and in the air, surface com-batants and aircraft will be detected longbefore they can target and launch their mis-siles against the sea base because of powerful,fully networked surveillance radars such asAdvanced Hawkeye and the Broad AreaMaritime Surveillance (BAMS) system. Evenif missiles are successfully launched, strikefighters with AESA radars, as well as extend-ed range Standard missiles, will give the seabase a greatly extended battlespace in whichto engage them, allowing multiple interceptopportunities against each incoming missile.Technology will improve this picture furtherwhen it allows better long range combatidentification and, in the event some missilesleak through, improved passive ships’ selfdefense systems alongside the active systemsalready planned.

Make Opposing SubmarinesPay For Their InevitableIndiscretions

In the undersea environment the challengesare different. Here, sensor performance islimited, reducing detection ranges, andmaking wide area surveillance a more asset-intensive endeavor. Furthermore, unlikenuclear submarines, which usually producea continuous acoustic signature, the bestdetection opportunities against non-nuclearsubmarines are both episodic and difficultto classify. On the other hand, there is aclose correlation between the steps a sub-marine needs to take in order get into posi-tion to attack a target, and the operationalindiscretions which provide the best detec-tion opportunities for ASW forces.Therefore, contacts must be prosecuted andreliably classified as quickly as possiblebefore they disappear back into the clut-tered background as an unknown contact.This puts a premium on ASW platformsthat can be deployed in numbers and dis-tributed throughout the sea base, close apotential contact quickly, and deploy amenu of high quality acoustic and non-acoustic sensors to reacquire and identifythe contact, classifying it as a false alarm, ortrailing and/or attacking it.

Get Back In the Counter-Surveillance Business

Finally, in the longer term, against more for-midable anti-access threats, the Navy willneed to get back into the business of deny-ing its opponent a reliable ocean surveillancecapability.The worst potential threats to thesea base emanate from missile attackslaunched from outside the sea base’s defens-es, but they therefore also demand that theweapon be launched from well beyond line-

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of-sight to its target. This in turn requireseffective over-the-horizon surveillance, clas-sification, and tracking from other sources,and that these sources also provide cueing toweapons timely and accurate enough fortheir terminal seekers to reacquire and lockonto the correct target and complete theengagement. Alongside the added reach ofsuch a centralized, networked, anti-accesssystem come potential new vulnerabilities ateach step of the engagement sequence, as theSoviet Navy learned during the Cold War.

The Force of the Future

The United States has long understood thevalue of single, full spectrum carrier battlegroups forward deployed in peacetime. It hasalso understood the value of concentrationin wartime when necessary; witness themulti-carrier operations practiced off thecoast of North Vietnam and those envisagedby the Cold War maritime strategy. But it hasbeen many years since concentrations of car-rier aviation were in a position to be sounambiguously dominant in the power pro-jection role, both in terms of its freedom tomaneuver in the face of opposing defenses,and in terms of its ability to produce decisiveeffects ashore. If one combines the effects ofthe precision weapons revolution (multiplekills per sortie) with the high sortie ratespossible on a large deck carrier, and thenconcentrates up to five or six of those carri-ers in one theater of operations, one isdeploying a combat force analogous in capa-bility to the Fast Carrier Task Forcesemployed to devastating effect in the last two

years of the war in the Pacific. Such a force,operating in dispersed or concentrated fash-ion, will be the key to meeting the greaterdemands on naval aviation in the new secu-rity environment described above.

For example, a force of six carriersincludes some 300 strike fighters, 30 E-2s,and 100 multimission helicopters, all operat-ing in mutual support of both each otherand expeditionary forces ashore.As PresidentBush noted at Annapolis recently, sinceDesert Storm, the number of targets ashorethat a single carrier is capable of destroyingin a single day has tripled.This means that aforward deployed carrier’s capability toinfluence events during the “golden hours”early in a contingency have been greatlyenhanced. It also means that when concen-trated, multiple carriers are now able to pro-duce effects ashore that would formerly haverequired many more wings of tactical aircraftoperating from local bases in the region,while at the same time protecting the seabase and extending that shield ashore.

The relative value of Naval Aviation as aguarantor of national security and an instru-ment of national will has never been greaterthan in today’s post-9/11 strategic landscape.From the Pacific campaigns of World War IIthrough the complete battlespace dominancedemonstrated during Operations EnduringFreedom and Iraqi Freedom, Naval Aviationcontinues to evolve as a decisive forcethrough ongoing incorporation of advancedtechnology. The necessary investments mustbe made to sustain this preeminent force toensure the United States’ continued accessand ability to shape world events.

Persistent surveillance, whether manned or unmanned, land or sea-based, is the foundation for success in all mission areas

in the new security environment.

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The long term security environmentis obviously less predictable than thenear term, and it is therefore more dif-

ficult to make specific assumptions about itslikely characteristics. But assumptions can bemade and trends identified in several areas.First, it is unlikely that the United States willhave to make a major continental commit-ment in order to preserve a balance of powerin Eurasia; second, it will have unpredictableaccess to bases along the Indo-Pacific littoralwhere it will most likely need to projectpower; third, it could face opponents withcapabilities ranging across the full spectrum ofconflict; fourth, new operational demandswill result in more sea basing and a more dis-tributed and persistent tactical air force; andfifth, technology trends will increasingly favorairborne as well as spaceborne sensor plat-forms, networking, persistence, decentralizedexecution, and robust, line-of-sight data links.

Major ContinentalCommitments on the Eurasian Land Mass Will Not Be Necessary

The key military aspect of the Cold War wasthe fact that the United States made a conti-nental commitment to Western Europe’ssecurity.The grand strategic purpose of thiscommitment was to contain Soviet power,preventing it from uniting the resources ofthe Eurasian landmass. The military expres-sion of this commitment was a large, contin-uing peacetime commitment of U.S. groundforces. It is extremely unlikely that any futurethreat to the Eurasian balance of power will

require a new continental commitment.Rather, should there be such a challenge, itwill likely arise in a maritime context.This isbecause nuclear weapons and political geog-raphy conspire to make significant landwardexpansion by Russia, China, India, or theEuropean Union at the expense of eachother all but unthinkable.

During the Cold War, Germany’s divi-sion and its non-nuclear status made itunable to defend itself against Soviet attackalone. The unification of Germany and thecollapse of the Soviet Union made Germanyand Russia much more equal in basic powerpotential, and also established a number ofmedium-size buffer states between them.Thus, a unified Germany would be muchless disadvantaged in a conventional militarycompetition with Russia. And Germany’scontinuing non-nuclear status could evolvein three directions in the future, none ofwhich would make major war betweenGermany and Russia likely.

First, current tensions aside, U.S. nuclearguarantees to Germany in the context ofNATO might simply continue. Second, thefurther intensification of European unifica-tion might substitute for these guarantees viaa European-based alternative.Third, and per-haps least likely, Germany might eventuallydevelop nuclear weapons of its own, whichwould undoubtedly create tensions, butwhich would in some ways deepen ratherthan weaken the barriers to major landwardexpansionism, at least by one nuclear powerat the expense of another.

The land border separating Russia andChina has also acquired buffer states such as

The Future Security Environment

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Kazakhstan and Mongolia, so that the twolarger countries abut only in China’s upperXinjiang province and more extensivelyalong the border between Manchuria andthe Russian maritime provinces. Both ofthese borders could become future sourcesof instability, but these instabilities should beconstrained both by the fact that China andRussia are likely to remain major nuclearpowers, and by the fact that the vulnerabili-ties along their land borders should tend tocancel each other out.That is, China is vul-nerable to separatism in Xinjiang province,which is near the base of Russian landpower, and Russia is vulnerable to sepa-ratism in its maritime provinces, which arenear the base of Chinese land power.

Finally, India is likely to maintain roughparity between its nuclear forces andChina’s, and furthermore, the political geog-raphy of the subcontinent will continue toprovide a powerful buffer against invasionalong the entire Indo-Chinese land border.Central Asia and the Indo-Pakistani subcon-tinent are likely to be enormous sources ofinstability, but geography and nuclearweapons make it unlikely that that instabili-ty will provoke a major ground war betweenIndia and China, and absent such a war,events on the ground in this region areunlikely to cause major shifts in the overallEurasian balance of power.

The most likely venue of great powercompetition and even war will, instead, havea more maritime focus. China and Japan isone obvious potential conflict dyad, andChina and India is another.A triangular com-petition among all three powers over controlof the energy flows from the Middle East andCentral Asia is also possible. The mediumpowers that sit astride the key sea routes, suchas Singapore, Malaysia, Indonesia, thePhilippines, Korea, and of course, Taiwan,will all have stakes in the outcome of such a

competition, and will all face competingpressures to balance or bandwagon againstdifferent perceived threats to their owninterests.And unlike the newly independentmedium powers in Central Europe, thesepowers are not part of any strong, transna-tional security organizations like NATO orthe EU.

U.S. Alliance Relationships andAccess to Overseas Bases WillBe Less Formal and MoreUnpredictable Than Those ThatObtained During the Cold War

The main Cold War alliance relationshipsbetween the United States and NATO andJapan benefited from a basic agreementamong the parties to each alliance on thethreats that justified it, the tools needed tooppose those threats, and the essential equal-ity of national interests and thermonuclearrisks at stake for all its members. Althoughthe United States dominated each alliance, italso committed itself to the most binding ofsecurity guarantees: the promise to use U.S.nuclear weapons, if necessary, to defend alliedterritory from attack, whether conventionalor nuclear. In return for this commitment,U.S. allies granted unprecedented access tobases within their territory and allowed theUnited States to station hundreds of thou-sands of troops.The rights of access and oper-ational activity granted by each host nationwere codified in formal status-of-forcesagreements and were therefore predictableand reliable enough to be assumed as a givenin Cold War military planning.

Both alliances were a response to theSoviet threat, and both continue after itsdemise, but neither any longer provides theUnited States assured access to local basesnear or along the long littoral from theMediterranean to the Sea of Japan.There, a

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better model for the alliance relationshipsthat will provide such access, when it isgranted, is the U.S.-Saudi relationship.

Originally formed early in the Cold War,the relationship grew in importance to boththe United States and Saudi Arabia after thefall of the Shah appeared to eliminate Iran asa buffer between the Soviet Union andPersian Gulf oil.Yet the United States gainedonly limited access to Saudi bases before1990 in support of its Rapid DeploymentForce (RDF), mostly in the form of portvisits and pre-positioning of ammunitionand other supplies. Iraq’s invasion of Kuwaitresulted in a decision by the Saudi monarchyto allow U.S. forces unlimited access, butthat decision was not made until four daysafter the invasion began, when Iraqi forceswere already poised on the Saudi border.i

After the war, the Saudis allowed U.S.combat aircraft to remain deployed, butrefused U.S. requests to pre-position abrigade set of heavy armor.ii During thedecade or so of Southern Watch, thosedeployed air forces were put under strictoperational restrictions, including a ban onflying any strike sorties from Saudi territory,even during crises such as Operation DesertFox in December 1998. iii

Saudi reticence about granting the U.S.unrestricted access to its bases continuedafter 9/11. Though many support missionswere flown out of Saudi bases during bothOperations Enduring and Iraqi Freedom,few if any combat missions were. And ofcourse, soon after the assumed completionof combat operations in Iraq, U.S. forces leftSaudi Arabia altogether.

Many factors explained this Saudi schiz-ophrenia about U.S. forces, even during theheight of their cooperation. The Saudiregime is a Sunni feudal monarchy that sitsacross a narrow sea from Iran, a Shia funda-mentalist theocracy; it is an Arab state that

enjoys good relations with Israel’s largest sup-porter; it is wealthy state with a small popu-lation that abuts several poorer states withlarge and growing populations. The UnitedStates could solve only some of the Saudis’security problems, while at the same timeexacerbating others, and it was always diffi-cult for the Saudi monarchy to determine thebalance between these two effects of theirmilitary cooperation with the U.S. Forexample, there is no question that the Saudiregime’s greatest domestic threat comes fromfundamentalist Islamists, and the U.S. militarypresence certainly served as a rationalization,if not a cause, for claims by Bin Laden andothers that the Saudi regime was failing in itssacred role of protecting the holy cities ofMecca and Medinah from the infidel.

Even before 9/11 and the two wars thathave followed, both the 1997 Report of theNational Defense Panel and the more recentHart-Rudman Commission report New WorldComing discussed why many of the uncertain-ties that characterized U.S.-Saudi militarycooperation during the period described abovewill be endemic in the new security environ-ment. For example, the latter noted that:

In dealing with security crises, the 21st

century will be characterized more byepisodic “posses of the willing” thanthe traditional World War II–stylealliance systems.The United States willincreasingly find itself wishing to formcoalitions but increasingly unable tofind partners willing and able to carryout combined military operations.iv

When the alliances that produce baseaccess are episodic and temporary, the accessthey produce will be as well.

Finally and perhaps most importantly,those who must consider granting access toU.S. forces in the future will do so without

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the prospect of receiving the security guar-antees against both nuclear and convention-al attack that the United States gave itsimportant Cold War allies.This will make itharder for them to determine whether giv-ing U.S. forces access will increase ordecrease their long-term security. For exam-ple, as the National Defense Panel argued,this might lead to limits on access for U.S.forces when potential allies face regionalrivals armed with weapons of mass destruc-tion.v Limits on access are also likely whenpotential regional allies face serious conven-tional threats.

This is not to argue that U.S. forces willgain no access to bases abroad. When facedwith clear threats to their sovereignty, manystates will ask for help, and when it is in theinterests of the United States to respond, itsforces will be given access. But this accesswill often come late, after a conflict hasalready begun; it will often be austere, in thatfew preparations will have been made inadvance; and it will often be withdrawn orsharply limited after the particular conflictthat generated it is resolved.

Future Military Opponents

One can imagine three types of militaryopponents for the United States in the newsecurity environment; peer competitors incompetition for energy resources with theU.S.; medium powers that seek or providenuclear technology: and terrorist groupswith global reach and their state sponsors.

Great Power Opponents

For lack of a plausible alternative, many focuson China as a future peer competitor of theUnited States.Certainly, it is possible to arguethat China will be wealthy and technicallyadvanced enough to play this role within

decades, if not sooner. Any country able tosustain a peacetime defense budget of $150billion a year or more, possessing a techni-cal/military/industrial complex capable ofdesigning, building, and operating modern,information technology-laden military sys-tems, could cause a reprise of some aspects ofthe Cold War military competition betweenthe U.S. and the Soviet Union. China doesappear on a path that would put those capa-bilities within its reach, and there are cer-tainly aspects of China’s geopolitical positionthat might cause it to embrace that path.

The main point is that any future conflictwith a peer competitor is likely to take theform of a struggle for control over the Indo-Pacific littoral because of the desire of somepower to control and assure access to the seasand littoral chokepoints that will continue tolink the world’s primary users of energy toits main supply. Given that the United StatesNavy now provides that service to the worldas a free good, it is ironic that the rise of apeer competitor would therefore be as like-ly to result from a retrenchment of U.S. mar-itime power in the Indo-Pacific region asfrom an overexpansion of that power.

In general, when maritime hegemony isused to assure rather than suppress free trade,it takes on the character of the trade that itassures; an exchange in which all achieveabsolute gains larger than they would in theabsence of such trade, but in which thelargest traders may achieve larger relativegains than others.Thus, maritime hegemony,when it is used to assure free trade, is rarelyitself the cause of great power conflict,because states generally ignore the balance ofrelative gains from trade unless they arealready in a military competition with theirpotential trading partners. This is a funda-mental difference between naval hegemonyand military hegemony, defined as the effortto develop supremacy of land power relative

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to one’s neighbors, because such supremacycreates the threat of landward expansion.Thethreat of landward expansion by definitioninvolves a threat to the basic sovereignty ofthe potential victim, and is therefore muchmore likely to provoke intense balancingbehavior than is naval hegemony.

A more likely source of conflict betweenthe U.S. and a peer competitor would arise ifChina and India became embroiled in astruggle for energy security that also involvedthe medium powers in the Indo-Pacificregion.One potential flashpoint for such con-flicts will be the unresolved status of islandchains such as the Spratleys, sovereignty overwhich may provide access to considerablereserves of offshore oil and/or natural gas.

The goal of the United States would beto play the role of the balancer of last resortin these competitions, and the power thatwill determine the balance in these compe-titions will be seaborne.This will put a pre-mium on forces that can independentlysurvive in and gain control over contestedsea and littoral battle spaces against all com-ers, and when necessary, can project powerrapidly ashore. The requirements for powerprojection ashore will stop short of an inde-pendent ability to wrest control of significantland areas from another great power, and willbe focused instead on the ability to deployair forces and, when necessary, ground forcesrapidly as an equalizer in land conflictsbetween medium powers and larger powers.

Thus, the United States should plan onmaintaining its global naval hegemony with-out allied assistance, but it should only planon fighting other great powers on land withthe assistance of another medium power. Inboth cases, in the event that a peer competi-tor emerges, the battlefields of the longer-term security environment will be muchmore lethal because the asymmetry inwealth and technological prowess that favors

the United States today will be gone or sig-nificantly reduced.

Medium Power Opponents

Alongside any great power competitions thatmight arise, or in their absence, there will bemedium powers that aspire to regionalexpansion, seek nuclear weapons or providethem to others, and/or support terroristgroups with global reach. This type of con-flict has been ubiquitous in the immediatepost–Cold War era, and were today’s “unipo-lar” moment to last forever, it would proba-bly be the only type of conflict for which theU.S. military needed to prepare. Iraq, Iran,and North Korea all fall into this category.

The nature of the wars that the U.S.might fight against such powers vary widely.Wars could be fought to prevent or reverseterritorial expansion by such powers, to stopthe development of nuclear capabilities, or toeliminate support and/or sanctuary for ter-rorist groups.Wars to prevent or reverse ter-ritorial expansion would most clearlycorrespond to the major regional contingen-cies that dominated DOD force planningbetween the end of the Cold War and 9/11.Wars to stop a nascent nuclear programwould start with relatively limited strikesagainst fixed targets, but would primarily bewaged to deal with the target country’s retal-iatory response. For example, the primarymilitary challenge of dealing with the cur-rent nuclear programs in Iran and NorthKorea is not to mount the attacks againsttheir fissile material production facilities, butto deal with the potential military responseto those attacks, whether that involves pro-tecting shipping and oil industry infrastruc-ture in the Persian Gulf from Iranian attack,or Seoul and its environs from North Koreaattack. Wars to prevent support for terroristgroups will require successful regime

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change, involving not only invasion but alsothe establishment of a new government, andthese wars, should the U.S. choose to wagethem, will most closely resemble the one theU.S. is engaged in today in Iraq.

The Global War on Terror

Operation Enduring Freedom sought notonly to attack Al Qaeda, but also to eliminatethe regime that provided it a base inAfghanistan and to prevent Afghanistan frombeing used for that purpose again. As such,Enduring Freedom probably represents thehigh end of the kind of wars that might befought against Al Qaeda or groups like it.This has led some to note the paradox thatthe war on terror makes the U.S. as con-cerned about weak, failed states, whose veryweakness creates a threat because it makesthem candidates for use as a terrorist base, asit has historically been concerned with stateswith rising power.

Whether the war on terror includesanother war like Enduring Freedom, it willalmost certainly include operations likethose being conducted today in Djibouti,where air, ground, and naval forces operat-ing from an austere base conduct smallscale, often covert anti-terror operationswithin the region broadly defined by theHorn of Africa.

Another military model for the futurewar on terror is represented by theProliferation Security Initiative (PSI), whichis a grouping of states willing in advance toallow their commercial ships to be boardedby other parties to the agreement in casethere are suspicions of the transfer of illicit,WMD-related cargos. The PSI is a specificexample of a much more general trend,which is that homeland defense in an age ofterror is a question of maritime security asmuch as any other factor.

Operational Demands on U.S. Naval Aviation

Three operational demands on naval avia-tion will dominate the future security envi-ronment. The first two will be lessdependent on the nature of the adversary,whereas the third, which is more of a trade-off than a demand, will depend heavily onthe nature of the opponent.The first is thatU.S. air forces will increasingly need todeploy and sustain themselves from the sea,rather than from local bases on land. Thisdemand derives not only from the changednature of alliance relationships describedabove, but also from the revolution in vul-nerability to fixed targets that is being causedby GPS. U.S. air forces are already exploitingthis revolution to “solve” the fixed targetproblem, but its full consequences will onlyarrive when opposing forces start to solvethe fixed target problem as well, which theyinevitably will. Once this process starts, thekey to successful projection of air power willbe to avoid dependence on fixed bases nearthe opponent, and instead to deploy andoperate from a secure, mobile sea base.

The second new demand will be that U.S.air forces adapt to the needs of U.S. groundforces on future battlefields. On those battle-fields, U.S. ground forces will deploy withsmaller, distributed force packages that, operat-ing independently from each other, will usehigh speed and a flexible scheme of maneuverto quickly reach and threaten key objectives. Inso doing, they will advance on external lines,both exposing their flanks and leaving pocketsof opposing forces in their rear. U.S. air forceswill have the responsibility of protecting theflanks and rear areas of these advancing forcesfrom efforts by enemy ground forces to con-centrate and maneuver in response.

To accomplish this task, U.S. air forceswill need to be in many different places at

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the same time, deploying networks of sen-sors and weapons able to quickly find, iden-tify, track, locate, attack, and assess thedamage of attacks against mobile targetswhen they emerge.To do this, U.S. air forceswill need to supplement today’s model ofone large, centrally managed, theater widenetwork with a model that supports manydistributed, self-contained networks, eachable to complete the kill chain autonomous-ly within its area of operation. In some lowintensity cases, such networks will formaround Expeditionary Strike Groups operat-ing alone, but in any case where there aremilitary threats the sea base will be formedaround an Expeditionary Strike Force thatincludes a Carrier Strike Group or Groups.

The Shift in Emphasis From Local Land Bases to Sea Bases

Both political and technological trends limitthe military’s access to local bases in regionswhere it will most likely need to projectpower. Formal alliances dating from theCold War, and the assured access to regionalbases that they provided, have declined inrelative importance compared to moreinformal coalitions formed after a conflicthas already begun. In these coalitions, U.S.forces must generally negotiate access toregional bases on the fly, and the access thatresults is therefore less predictable in advanceof a conflict than in the past.

At the same time, technological trends aremaking fixed targets more and more vulner-able to attack. In particular, when potentialopponents follow the United States in mar-rying precision guidance technologies tocruise and ballistic missiles they will be ableto hold fixed bases within a radius of up to a1000 miles at risk of conventional attack bycruise and ballistic missiles against whichdefense is extremely difficult.

Political Constraints on Access to BasesAshore. The political constraints on accessto foreign bases affect land and sea-basedforces differently.The main difference is notthat one mode needs overseas bases whilethe other does not, but that land bases launchweapons while naval bases do not.This dis-tinction makes naval bases less threatening tothe host nation, not just because it makesthose bases less of a target, though it maycertainly have that effect as well, but becauseit separates the host nation politically fromthe actions taken by the U.S. naval forces thatuse those bases.

This is a function of the range andendurance of naval platforms, which go to seafor months at a time, and often operate liter-ally around the world from their bases.Certainly, when ships go to sea, they are sup-ported by an extensive train of supportingvessels, which replenish supplies of fuel oil,dry cargo, and, in the midst of a conflict,ammunition. But this umbilical connectingdeployed navy combatants to the shore islargely indistinguishable from normal com-mercial activity, and is in fact often conductedby civilian-crewed ships that are essentiallyindistinguishable from their purely commer-cial counterparts.Thus, for example,when theU.S. Navy first began regular Indian Oceanbattle group deployments in the late 1970safter the fall of the Shah, its oiler and storesships were able to obtain needed suppliesfrom a variety of countries along the IndianOcean littoral, none of which were willing toprovide any level of base access ashore toland-based American forces.

This distinction is reflected in actual legalarrangements. For example, everywhere theUnited States has access to overseas bases forland-based forces it has an accompanying setof agreements with the host nation abouthow those forces will or will not be used.Thus, in a recent example, after the Taiwan

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straits crisis of 1997, the United States appar-ently sought to negotiate with Japan overfuture guarantees that bases on its territorywhich were not available in 1997, would bein the future under similar circumstances. Nosuch negotiations were necessary regardingthe use of Yokosuka and other U.S. Navyfacilities in Japan, even though the primaryU.S. military response to the 1997 crisis wasnaval, and involved forces homeported inJapan. Likewise, land-based forces have expe-rienced significant constraints on the use ofbases in the Persian Gulf region duringOperations Enduring and Iraqi Freedom,while sea-based forces have enjoyed unlimit-ed access to naval facilities in the same region.

Certainly, this asymmetry in favor of seabasing does not come without its costs, andsea-based forces may be less cost effectivethan analogous land-based forces in thosecases where the latter have assured access tolocal, prepared bases in advance of a conflict.But as has become eminently clear, this levelof access will be much less common in thefuture security environment than it was dur-ing the Cold War.

Access for land-based forces can be con-strained in both time and scope. For exam-ple, a country might deny American strikeaircraft based there permission to bomb aneighbor, but allow aircraft flying supportingmissions to operate, as has been routine inthe Persian Gulf region since Desert Storm.Similarly, a country that had allowed theUnited States to pre-position war materialto support rapid deployment of land-basedforces in a crisis will be likely to supportsuch a deployment only under a particularset of circumstances, against a particularopponent. Also, a country might or mightnot allow a U.S. force to stage through itsterritory or its air space on the way toanother country’s bases, and again, there willbe cases where a country will allow all forces

to do so, and other cases where only supportforces such as tankers and airlifters will beallowed to transit. Such access to enroutebases is necessary to any major deploymentof land-based forces, both because AirMobility Command airlifters must stagethrough them, and because air-refuelingtankers must operate from them in order torefuel deploying aircraft.The same constraintapplies to global bomber operationslaunched from the continental U.S., whichare utterly dependent on access to enroutebases on foreign territory for use by KC-135s and KC-10s.

In addition to gradations in the scope ofaccess granted U.S. forces, are gradations inthe timing with which that access is grant-ed. As noted in the first section, it took theSaudis four days after the Iraqis invadedKuwait to decide that a massive deploymentof American forces would be in their securi-ty interest.The speed of the deployment thatfollowed was inestimably aided by the mas-sive pre-positioning of U.S. equipment thatthe Saudis had agreed to during the ColdWar.Thus, a country that already had a majormilitary relationship with the United States,and which had allowed extensive pre-posi-tioned stocks of equipment to be deployedon its territory in anticipation of a scenariolike the one it faced in August 1990, still tookdays to decide how to respond. A countrywith a more tenuous relationship with theUnited States, or greater concerns about theprojected military operation, might refusesuch access, as Turkey did at the outset ofIraqi Freedom. Finally, access once grantedcan also be revoked, as happened abruptly inthe Fall of 2005 in Uzbekistan.

Operations Enduring and Iraqi Freedomhave provided myriad examples of these var-ious gradations of access in both time andscope for land-based forces. The centralpoints about this experience are two: the

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access eventually gained has over timebecome extensive, but the process that pro-duced this access began after the need forthe access emerged, was protracted, and theresults were utterly unpredictable from thevantage point of September 10, 2001.

Military Constraints on Access to BasesAshore. The technical trends effecting themilitary security of overseas bases provide acase where the demands of the near and farterm security environments appear to rein-force each other, even though the source ofthis similarity is different. This is becausefixed bases within a radius of 500 to 1000miles of an opponent are likely to becomeincreasingly vulnerable in the near to midterm to conventional attack by GPS/INS-guided ballistic and cruise missiles. Over thelonger term, this vulnerability to over thehorizon attack will extend to large ships atsea,but in the near to mid term, such ships arelikely to be more survivable than fixed landbases as long as they stand off over the hori-zon from an opponent. Satellites, and espe-cially those in low orbits, will also becomevulnerable in this time frame. Least likely tobecome vulnerable out through the far term,some 30 or more years from now, are under-sea platforms. Fast, quiet nuclear submarineswill remain the least vulnerable of all basingmodes because antisubmarine warfare (ASW)is least affected by the technical trends thatwill potentially transform other warfare areas.Thus, ASW against modern nuclear sub-marines will remain both extremely demand-ing technically, very expensive, and still alargely fruitless endeavor.

The trends in the vulnerability of fixedbases within a theater will be driven in par-ticular by the marriage of cheap, widelyavailable GPS/INS guidance technology andconventional sub-munition payloads withexisting, mobile, tactical ballistic missiles

(TBMs) and cruise missiles. Cruise missileswill likely be chosen if an opponent wishesto extend his reach beyond about 600 km.vii

Such cruise missiles might actually have morein common with small aircraft than with cur-rent cruise missiles like Tomahawk, andmight derive their survivability less from highspeed and low radar cross section than fromtheir ability to blend in with a noisy back-ground and deny an opponent positive iden-tification.viii This discussion will focus onTBMs because they are already ubiquitous.

Before discussing the impact of GPS/INS, it is important to establish what isalready true about existing mobile TBMcapabilities. TBM defenses have alreadyproven to be at the edge of the scientific-technical capabilities of the United States,and even assuming effective TBM defensesin the future, they will likely be on the los-ing end of the cost-exchange ratio betweenthe attacker and the defender.Directed ener-gy weapons may change this relationship inthe distant future, but even directed energyweapons will be most effective against anti-ship missiles whose warheads must have ter-minal seekers, because it is more difficult toharden the latter against a laser or highpower microwave than it is to harden anINS/GPS-guided warhead used in attacksagainst fixed targets.ix Heretofore, the TBMthreat has been leavened by the fact that theyhave been very inaccurate.Armed with con-ventional warheads, their military effectshave been both low and unpredictable, andarmed with nuclear, chemical, or biologicalwarheads, their use would bring the vastlysuperior American deterrent into play.

GPS/INS will lead to a quantum leap inconventional TBM capabilities because itwill give them the accuracy needed to attacksoft, fixed military targets with conventionalsubmunition payloads. This is a capabilitythat has already been deployed by the U.S. in

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the form of the U.S. Army’s Tactical MissileSystem (ATACMS). Single stage TBMs likethe Chinese M series already provide rangesof 300-600 km (185-375 miles), payloads of500 kg (1100 lbs), and conservatively esti-mated accuracies of 100-200 meters (330-660 feet). A 500 kg payload of simplesubmunitions like the M-77 grenade candestroy soft targets over a circular area of twomillion square feet centered at their point ofrelease. Even with the relatively low accura-cies assumed above, TBMs like this wouldwreak havoc on airfields and ports withintheir range. For the purpose of this discus-sion, I will focus on airfield vulnerabilities,and in particular on those vulnerabilitiesmost relevant to the mid to far term securi-ty environment.

Airfields within range of opposing TBMswill be inherently vulnerable in the expedi-tionary environments typical of likely futureair operations for four reasons. First, simplybuilding the hardened shelters to protect five72 aircraft wings of tactical fighters is amajor, multi-billion dollar investment thatfew potential allies are likely to make ontheir own. Second, in a world where thelocation of future conflicts is less predictablethan it was during the Cold War, the U.S.will not be able to invest in hardening air-fields in all the potential areas where it maybe called on to fight. Third, even in caseswhere the United States did make thisinvestment during the Cold War, as in SaudiArabia, it still proved too expensive to pro-vide shelter to the thousands of U.S. person-nel which must live and work on the base;hence the enormous tent cities which wereerected on base, which would remain alucrative target even at the hardest base.Finally, it is simply impossible to providehardened shelters for the various large, highvalue support aircraft which are integral toany expeditionary air operation, such as

AWACS, JSTARS, Rivet Joint, KC-135 andKC-10 tankers, and outsize airlifters like theC-5 and the C-17.x For all these reasons, itis likely at some point in the mid to longterm future that large scale, expeditionarydeployments of tactical combat aircraft andsupporting assets will become limited by theneed to avoid bases within 1000 miles of anopponent’s territory.

This constraint will, at a minimum,reduce by half or more the sortie rate of agiven size force of tactical aircraft, andincrease the cost in terms of additionaltanker support and bases for those tankersnecessary to give that force the range toattack a given set of targets. Perhaps moreimportant, there will be circumstances dueto the political geography of a particularconflict in which the only bases potentiallyavailable will be within range of an oppo-nent’s missile force. This will lead to caseswhere land-based tactical aircraft will bedenied access to a given theater altogether,or at least until the threat to their bases hasbeen suppressed or eliminated by otherforces.

The Special Case of Bombers andOverseas Bases. Land-based bombers usetheir much greater range than land-basedtacair to reduce the number and/or thepolitical salience of the overseas bases theyuse, and to increase the standoff range ofthose bases from the opponent. Politically,bombers can reduce their vulnerability todenied access simply by increasing the prob-ability that an amenable ally can be foundwithin range of the opponent.They can alsoreduce their vulnerability to being deniedaccess by taking advantage of the fact that acountry is more likely to allow tankers ratherthan combat aircraft to operate from its bases.Taken to its extreme, this latter tactic caninvolve 30-40 hour round trip missions for

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the bomber and its crew between the UnitedStates and a target half way around the world.In these operations, the bomber never uses aforeign base, but the vast array of tankers thatmust pre-deployed along its route must do sointensively. Thus, it is almost never the casethat long range bombers eliminate all depen-dence on access to foreign bases.What theydo in almost all cases is lessen that depen-dence below the political threshold that canlead to access denial.

Added range is not a free good, which iswhy bombers are much larger and muchmore expensive than tactical fighters, andtend to be slower. Also, though their sizegives them larger payloads, the added rangeover which they carry those payloads leadsto reduced sortie rates. Finally, in contestedair space, bombers cannot defend themselvesagainst opposing air defenses, which pre-cludes independent operations by B-52s andB-1s, and precludes daylight operations byB-2s.These tradeoffs between bombers andland-based tacair will become more impor-tant when military vulnerabilities at overseasbases are added to the political vulnerabili-ties that already exist. Assuming that therewill be limits on the range of these threatsfor the foreseeable future, they will improvethe relative advantages of long range aircraftcompared to land-based tacair, because basesoutside that range will not need to bedefended and/or hardened.

Distributed Air to SupportDistributed Ground Forces

“…the long thin columns of vehiclespenetrating through hostile territorywere very weak, seemingly highly vul-nerable to attacks on their flanks.Tactically, the columns were of courseall flank and no “front.” …(But) solong as the invasion columns kept up a

high tempo of operations, their appar-ent tactical vulnerability was dominat-ed by their operational advantage sincethe defender’s intercepting and block-ing actions would always be one stepbehind…The whole operation obvi-ously rests on the ceaseless mainte-nance of momentum.Organizationally,this implies a very restricted deploy-ment of heavier/slower artillery, theneed to keep the supply tail light andfast moving will restrict the amountthat can be deployed.” xi

This description of the German Army’sinvasion of France in the Spring of 1940applies almost verbatim to the U.S. Armyand Marine Corps’ initial operations againstIraq in Operation Iraqi Freedom. Theseoperations will likely serve as a futuremodel for expeditionary ground forceoperations.

In such operations, ground forces willlikely strike from several locations at the sametime, operating from expeditionary bases onexternal lines surrounding the opponent.Because of the expeditionary environment,and because of the need to maximize thespeed and freedom of maneuver of theinvading force, the size and firepower of theinvading force will frequently not be suffi-cient to win a straight attrition battle withopposing forces. Rather, that force will seekto use speed and maneuver to confuse andparalyze the opponent’s command system,and to quickly penetrate and descend on theobjective from several directions.

Air forces must play a central role in suchoperations for two reasons. First, when thedesired shock effect depends so directly onthe maintenance of momentum, and whenground forces must be kept light to create thatmomentum, air support becomes a key sourceof fires enabling either the rapid elimination of

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obstacles to the ground force’s advance, ortheir avoidance and later reduction.

Second, such operations absolutelydepend for their success on the creation ofchaos and confusion among opposing forces.In cases when the opponent maintains itscohesion at the operational level, as forexample did the Allied forces deployed inthe Ardennes during the Winter of 1944, allof the potential tactical vulnerabilitiesdescribed above become real, and the pene-trating columns of the attacker are cut offfrom their supplies and attacked by opposingforces able to concentrate and maneuveragainst their weak, exposed flanks.A major ifnot dominant mission of future air forceswill be to detect and destroy such concen-trations down to the company level beforethey can strike. This requirement is one ofthe main drivers behind the need for airforces to develop mobile target kill capabili-ties against opposing ground forces.

The specific requirements for such amobile target kill capability will be discussedbelow, but the main requirement is for airforces capable of being in many places at once,to match the distributed nature of the groundbattlefield. Distributed air forces assure thattargets can be struck quickly when the needfor such strikes arises. In this respect, themobile target problem will create demands fora very different force than will the fixed targetproblem. For example, in the latter case, thelack of time urgency and the desire for effi-ciency may call for large platforms with largeweapon payloads that can attack their targetsat leisure. Such a force would be inappropriatefor the mobile target problem because at anyone time, it would only be within minutes ofstriking one part of a distributed battlefield.

In addition, in cases where the opponenthas significant air defenses, the demand for adistributed air force must be met from thevery outset of the conflict with absolute reli-

ability, given its’ role in the combined armsbattle. This is one of the main reasons whynaval aviation is pursuing the cost-effective,all aspect stealth that F-35C will provide. Itwill enable distributed operations from thefirst day of any conflict without the priorneed for a large defense suppression cam-paign, or the continuing need for dedicateddefense suppression escorts.

Distributed operations of this type willlikely dominate the future regardless of theopponent because they are a potential solu-tion to problems that occur at both the lowand high ends of the conflict spectrum. Atthe low end of the spectrum, distributedoperations make it possible for the combat-ant commander to deploy a smaller, lighter,more sustainable force for the initial opera-tion to repel or assault an opponent’s forcesin what will often be an austere environ-ment against lesser powers. At the high endof the spectrum, it is possible if not likelythat distributed operations will prove anecessity, both to reduce the ground forces’dependence on vulnerable fixed bases andstaging areas that can be attacked by theopponent, and to avoid the need for break-through battles against that opponent’s forcesin order to envelop and destroy them, per-haps via the means of multiple, simultaneousvertical envelopments.

Concerns About Casualties andCollateral Damage

America’s supposed aversion to casualties inpost Cold War conflicts has been much dis-cussed. Fear of casualties often measured inthe thousands or even tens of thousandsdominated the debate over whether tolaunch a ground war in Desert Storm. In theevent, casualties during Desert Storm wereorders of magnitude lower than expected,leaving the question of America’s tolerance

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for casualties open for debate.xii Then theevents of early October 1993 in Mogadishu,Somalia seemed to resolve the debate.xiii

The death of a small number of Rangers andDelta Force troopers abruptly led the UnitedStates to abandon that operation. A growingconsensus developed that the United Statescould be stopped in its tracks with the deathsof a few of its soldiers, leading some to ques-tion the viability of its enormous but seem-ingly unusable military power.

The later experience in Kosovo certain-ly did not provide evidence that the UnitedStates was not casualty averse, and it alsobrought to the fore the related question ofrules of engagement and whether its fearsof causing collateral damage to civilians andcivilian infrastructure had come to ham-string its operations to the point of impo-tence. For example, NATO air crews wereordered to remain above 15-20,000 feetthroughout the entire conflict because itwas only at that altitude that they remainedimmune from Serbian air defenses, and, ofcourse, ground forces were foresworn fromthe outset. This restriction also reducedNATO’s ability to distinguish betweenSerbian forces on the ground, Kosovarfighters, and fleeing refugees, making it allbut impossible to stop or limit the ethniccleansing being conducted by Serbian armyand police units in Kosovo, driving NATOpolitical and military leaders to adopt agradual strategic bombing campaigndesigned to coerce Serbian compliancewithout causing excessive damage to thecivilian infrastructure, which took monthsto succeed.

As of this writing, Iraqi Freedom has notprovided unambiguous evidence on this ques-tion, but it is clear that for those who dooppose the war, U.S. casualties are a majorcause of that opposition.The explanation forthis aversion has more to do with the

strength of the United States’ position in theworld, rather than the weakness of its leadersor its people.The U.S.’s basic security meansthat it rarely if ever has to fight wars ofnecessity against formidable opponents, andthe general weakness of the enemies it doesfight means that U.S. forces are rarely drivenby military necessity to make attacks againsttargets where there is any but the smallestchance of collateral damage.

On the first point, the United States is themost secure country the world has ever seen:

“..(which) leads to something of a para-dox: Although solving many globalproblems requires active U.S. involve-ment, Americans do not see them asvital to their own interests and they areunwilling to expend much effortaddressing them… Americans wouldlike to coerce others to do what theywant, but they aren’t willing to riskmuch blood or treasure to make surethey do.”xiv

In this view,America’s aversion to casual-ties, and the degree to which political lead-ers will constrain how the military fights inorder to reduce its exposure to casualties willdepend on the stakes the United States hasin the conflict. Because of the great over-hang of American power in today’s securityenvironment, and because of its basic securi-ty, few if any conflicts are likely to engage itsvital interests, and many conflicts, likeKosovo, the first Gulf War, and even the cur-rent war in Iraq, will be viewed by manyAmericans as wars of choice. Using the samelogic, concerns regarding attacks that mightcause collateral damage grow steep when itis difficult, against a very weak opponent, toargue that military necessity allows no alter-native to launching those attacks.

This basic structural paradox sets the bar

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extremely high for the U.S. military, becauseit must win while keeping its losses and col-lateral damage extremely low by historicalstandards. Certainly, the pressures in thisregard will vary somewhat, depending onwhether a conflict is a major contingencylike Iraqi Freedom, or instead, a humanitari-an intervention in Latin America or CentralAfrica.Yet in the absence of major war witha great power, there is little prospect that theU.S. military will see this bar lowered.

The main military consequences of thisreality will be a growing demand forweapons which can stand off at a distancefrom enemy defenses and avoid direct fireengagements with their targets at shortranges, but also growing demands for veryprecise identification of targets before theyare attacked and very precise results whenattacks are approved. In many cases, such as inattacks from the air against high profile, fixedtargets on the ground, precision weaponshave or soon will solve these problems. Inother cases, such as in attacks from the airagainst military vehicles or convoys outsideof contact with friendly ground forces, theproblem of combining precise identificationand weapon effects with essential immunityfrom attack is far from solved. In still othercases, such as in today’s urban counter-insur-gency operations in Iraq, it is only possible toimagine solutions to this problem throughthe deep integration of air and ground forcesdown to the smallest units.

Another consequence of this problem is atradeoff between concepts of operationwhich devolve the maximum degree ofauthority to execute operations to theengaged units, and those that concentratedecision making and execution authority atcentral operations centers. In an ideal world,distributed operations would lead to radical-ly decentralized execution authority, therebyspeeding up the decision cycle, maximizing

the prospect that fleeting targets could bestruck before they disappeared again, andreducing the overall operational risks associ-ated with distributed operations. On theother hand, when political and military lead-ers have to weigh the political costs of eithercasualties or collateral damage in limitedconflicts, they will remain reluctant to allowsuch decentralization, and concepts of oper-ation will tend toward centralized controland execution.

The perceived cost of casualties and col-lateral damage would certainly change inwars of necessity when military necessitydemanded it. But it is important to note thatconcepts of operation bred in today’s securi-ty environment will have a tendency to“reify” themselves in the doctrine and forcestructure of tomorrow’s forces. This issue isof particular importance to air forces, whereboth the desire and the ability to centralizeexecution is felt most strongly by militaryleaders prosecuting wars of choice againstweak opponents, but where the conse-quences of building centralization intofuture doctrine and systems could be devas-tating in the event U.S. forces faced moreformidable opponents.

Technology Trends in the NewSecurity Environment

Longer term trends in technology are moredifficult to predict, but some can be identi-fied with more or less confidence. As in theprevious discussion of operational demands,some trends in technology are general andapply across all or many mission areas, whileothers apply most strongly to a particularmission area. The following discussion willemphasize those trends that are likely toapply across all or most mission areas.

The conventional wisdom in the U.S.defense department regarding the future of

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military technology appears to contain at leastfive assumptions or desires: that space-basedsensors will play a larger role in future opera-tions; that sensors, however based,will increas-ingly be linked to form networks, rather thanused independently; that unmanned vehiclesin the air, on the ground, and on and belowthe surface of the sea will increasinglytakeover missions now assigned to mannedplatforms; that more and more battlefieldinformation processing, decision making andcontrol will be centralized in rear area opera-tions centers; and that the bandwidth toenable networks, operate unmanned vehicles,and support rear area operations centers willbe available. Certainly, all of these trends arereal and all are likely to continue, but at thesame time, each can also be taken too far.

Space-Based Sensors

There is a long history of the tactical ex-ploitation by the defense department of so-called national capabilities, or space-basedsensors. These efforts exploited assets thatwere already in orbit that were designed,procured, and operated by the intelligencecommunity. Today, there is much discussionof space-based systems that would be devel-oped and operated jointly by DOD and theintelligence community, and which wouldtherefore be designed from the outset withDOD’s as well as the intelligence communi-ty’s needs in mind.

It is easy to show what the inherent limitsof airborne sensor platforms are compared tospaceborne sensor platforms. Airborne sen-sors can only see out to the horizon, out toperhaps 200 miles at the most. Spacebornesensors looking down at the earth from lowearth orbit can see a patch of ground at leasttwice that area, and from geosynchronousorbit, satellites can “see” almost an entirehemisphere. Airborne sensor platforms are

also easier to shoot down then satellites andmust generally standoff some distance fromhostile air space until opposing defenses aresuppressed or destroyed.

By contrast, the limits of spaceborne sen-sors are more subtle and generally require atechnical understanding that is largely absentfrom most public debates. For example, air-borne sensors can dwell in a given area foran extended period of time, with its sensorperformance limited only by line-of-sightconstraints. Satellites, on the other hand, facea tradeoff between low orbits, where sensorperformance is maximized but dwell time inany one area is measured only in minutes,and much higher synchronous orbits, wheredwell time is maximized but where manysensor phenomenologies are ineffectivebecause of the great distance to the earth’ssurface. For example, radar and optical imag-ing sensors cannot be deployed in synchro-nous orbit.

Therefore, to achieve the dwell time nec-essary for surveillance as opposed to recon-naissance, radar and optical imaging sensorsin low earth orbit must be deployed in con-stellations of 20-40 satellites in order toensure that one is over the area of interest atany time. By contrast, a single airborne sen-sor platform can provide continuous surveil-lance of a given area for many hours, andthree or four can provide 24 hour surveil-lance indefinitely.

Airborne sensor platforms can also deploylarger antennas with more powerful and con-tinuous power supplies. This is particularlyrelevant in the case of MTI radars, whoseperformance is very sensitive to power andaperture.Airborne sensor platforms also havesignificant advantages when used as SIGINTplatforms against highly directional signalssuch as those generated by air defenseengagement radars, whose main beams prop-agate horizontally rather than vertically.

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Because of these various tradeoffs, spaceand airborne sensor platforms should com-plement each other, but as in many missionareas, it is difficult for many casual observersnot to see two different platforms deployingthe same types of sensors as duplicative.Addto this the fact that a satellite remains a vast-ly more expensive method of deploying asensor than an airborne platform and it iseasy to see how a push to transform spacereconnaissance into space surveillance couldhave unintended and undesirable conse-quences for the Department of Defense if itcomes at the expense of the ability to fundairborne surveillance platforms.

Sensor Networks

Whether deployed in space, in the air, on theground, or under the sea, sensor performancecan often be improved dramatically when theoutput of multiple sensors is compared andfuzed. For example, even the most advancedRF antennas have inherent limits in their res-olution which, at longer ranges,produce errorsin target location measured in 100s if not1000s of feet in azimuth for MTI radars andELINT receivers. These errors can be elimi-nated or dramatically reduced if several sensorsare deployed within line-of-sight of the targetand of each other and their output data-linkedand processed.Two or three networked MTIradars using trilateration can precisely locateand track a moving target, and two or threenetworked ELINT receivers using some com-bination of TDOA and FDOA processing canprecisely locate a hostile radar.

Furthermore, in many cases, networkingcan enable a significant reduction in the costof individual sensors. For example, the bestELINT antennas with angular resolutionsmeasured in single degrees or even fractions ofa degree require large platforms like the RC-135, and are therefore very expensive.By con-

trast, the antennas used in a TDOA/FDOAnetwork can be extremely small and cheapbecause the angular resolution of the nodes inthe network become irrelevant to its perfor-mance. In this extreme case, a network com-prised of several very simple nodes not onlyoutperforms a single, very sophisticated plat-form, but is also much cheaper.

But many ignore the assumptions hidden inthis comparison.First and most obviously, suchnetworks fail deadly. That is, they require a cer-tain number of nodes to function, anddeprived of even one node they fail complete-ly. There is no graceful degradation in aTDOA/FDOA ELINT network if its individ-ual sensor nodes are not also designed to oper-ate alone. Second, in the case where networkdesigners anticipate this vulnerability, they canseek to deploy redundant sensor nodes tocompensate for losses or malfunctions, but inthis case they must also ensure that a highdegree of self-organization and self-healing isbuilt into the network. Otherwise, the addi-tional, redundant sensor nodes can become asource of error rather than insurance.Finally, indenied or contested environments, it is oftendifficult to deploy and operate any sensors atall, never mind a redundant network.

An alternative approach to networkdesign would look at networks as an oppor-tunity to greatly expand the potential capa-bilities of individual sensor platforms thatcan function autonomously if necessary.Certainly, in the near to mid term, there isthe need for considerable experimentationto determine both the strengths and weak-nesses of networking, and a strategy that ledto the deployment and use of networks thatfailed safe rather than deadly would have realbenefits.There is also considerable promise inthe use of networks where the nodes are socheap as to be truly expendable. These willusually be networks of passive sensors andwill therefore also provide the potential for

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covert surveillance. Such networks wouldprovide an ideal venue for experimentationwith self-organizing and self-healing systems.

Unmanned Aerial Platforms

Taking the aircrew out of an airborne plat-form can clearly solve some important mili-tary problems. High endurance, high altitudeUAVs like Global Hawk have amply demon-strated their worth as sensor platforms, andboth the altitude and endurance of their oper-ation are simultaneously the source of theirrelative value and the result of taking the air-crews out of the platforms and putting themon the ground. By the same token, a cruisemissile like Tomahawk that can fly up to 1000miles into contested air space eliminates theoperational tradeoff between deep penetrationattacks by platforms like the B-2 and the needto keep air crews within range of helicopter-based combat search and rescue (CSAR) assetswhose range is limited to 2-300 miles.

The next step in unmanned aerial plat-forms is assumed by many to be some sortof unmanned combat air vehicle (UCAV)which would deploy both sensors andweapons into contested air space andreturn to be reused again. In many eyes,UCAVs are viewed as successors tomanned strike fighters. This implies manythings, among them that UCAVs can beprovided the target recognition and situa-tional awareness capabilities that air crewsprovide strike fighters.

For example, target recognition ofteninvolves the generation and interpretationof high resolution images. At some pointin the future it may become possible toautomate that process, but today and for anumber of years target recognition willrequire people to interpret the images.Situational awareness allows many air-borne vehicles to operate in the same air

space without collision, and it also allowsaircraft to respond immediately to a vari-ety of hostile threats, either to avoid themor attack them. Air crews accomplish thisfunction by constantly monitoring a vari-ety of sensors and cues, including predom-inantly what they collect themselvesvisually on a continuous basis.As with tar-get recognition, it is difficult to imagineautomating this function.

In short, providing target recognition andsituational awareness capabilities to UCAVswill likely still require crews, but those crewswill be physically separated from the multi-tude of sensors that provide that capability.The bridge linking the crews to their sensorswill be data links, some of the constraints ofwhich will be discussed below. The oneunambiguous advantage of separating aircrews from their platforms is the increase inthe latter’s range and endurance that becomespossible. For example, in the case of carrieraviation, whatever payloads are deployed oncarrier-based UCAVs, the ability to deploythose payloads on platforms with a 1500 mileradius and 12 hour endurance will be the fac-tor that drives their adoption.

Centralized Air OperationsCenters

Since the first Gulf War, combined air opera-tions centers (CAOCs) and other rear areaprocessing facilities have played an increasingrole in air operations. The use of the wordcombined implies correctly what the functionof these centers has been – to combine a seriesof normally separate streams of intelligence,surveillance, and reconnaissance assets into afuzed picture of the battlefield to supportdecision making by high level leaders. ACAOC can also be described with equalaccuracy as a means of centralizing decisionmaking authority on the battlefield.

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Specifically, CAOCs are a place to fuzethe output of many independent sensors,whether spaceborne, airborne, on the sur-face or under the sea. When it is necessaryor desirable to create networks of sensors,CAOCs are often a place to do the uniqueprocessing that gives those networks theirpower. And certainly, if UCAVs aredeployed in large numbers, CAOCs or reararea locations like them will be one place toput the ground crews that will give thoseassets their target recognition and situation-al awareness capabilities.

Such centralization has two major conse-quences, one that is obvious and that will bediscussed in the next section. The otherconsequence is more subtle. Operations byeven modest-sized forces on cluttered bat-tlefields generate the need for thousands oftactical decisions a second, most of whichare obviously made on the spot in real timeby small units and individuals who then alsobecome the means of executing those deci-sions. If one seeks to take any significantpercentage of this activity and physicallyseparate the means of decision from themeans of execution, and if one wishes topreserve if not accelerate speed and respon-siveness, then both the number of indepen-dent, rear area decision makers and thebandwidth connecting them to their meansof execution become fundamental determi-nants of the possible pace and scope of mil-itary operations.

Of course, this is ironic because CAOCshave for the last decade increasingly been thescene of successful efforts to speed up deci-sion making and execution, but this progresshas occurred during a phase when the mainobstacle to fuzing or networking informa-tion was technical rather than bureaucratic.It also has occurred during conflicts inwhich U.S. forces were still designed andtrained to operate without ISR fusion and

networking if necessary, in which operationsdirectly supported by the CAOC were avery small albeit important subset of thewhole, and in which the forces deployed bythe opponents were vastly inferior, particu-larly in qualitative terms.

Secure High Data RateCommunications

In a future where it is assumed that manytactically relevant sensors are deployed inspace as well as in the air and on the surface,that sensors are often formed into networks,that sensors and weapons will deploy intocontested air space on unmanned platforms,and that ISR information is combined andweapon release authority centralized in reararea operations centers, one capability aboveall others will be required—the ability tomove vast amounts of data between many100s if not 1000s of mobile platforms, reli-ably and over great distances.The solution sofar to this emerging issue has been to leasebandwidth on commercial satellites.

But if future opponents have even mod-estly better electronic warfare capabilities thantodays’ opponents, never mind if a true peercompetitor should emerge, than those highdata rate communication links will have to besecured in the face of efforts to jam them.Today, in the entire Department of Defense,there is not a single communication systemthat comes close to achieving this objective.

The problem is that data rate and jamresistance directly compete for the samebandwidth. For example, UAVs like GlobalHawk and Predator often use commercialsatellite communication systems operating atKu band (10-15 GHz) when they need torelay their sensor outputs over the horizon.These satellites are designed to maximizedata rate and can support links withthroughputs of 10s of MBs/sec. but are thor-

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oughly vulnerable to simple noise jammingfrom anywhere within their uplink antenna’sfootprint, which for a geosynchronous orbitis always large. By contrast, Milstar, a DODsatellite system which operates at even high-er Ka band frequencies (and therefore high-er bandwidth), is optimized toward jamresistance and will only support data ratesmeasured in 10s of KBs/sec; i.e. severalorders of magnitude less. Hybrid waveformsat Ka band used on Milstar II that seek acompromise between jam resistance and datarate can support data rates of roughly 1.5MBs/sec, or the equivalent of a T-1 line. Atlower frequencies, such as the ubiquitousUHF SatCom systems which are most use-ful to tactical forces because they do notrequire expensive terminals and highlydirectional antennas, such as those used byMilstar, there is much less bandwidth avail-able, and therefore both data rates and jamresistance are inherently low.

One option for addressing this problemwithin a specific area of operations is to relymore on networks of airborne relay platformsthat are linked by line-of-sight communica-tions. Such airborne networks have the

potential to address the data rate/securitytradeoff in at least three ways. First, theground footprint of an airborne receiveantenna is much smaller than for a satelliteantenna, which means that the area fromwhich an opposing jammer could introduce aspurious signal into the antenna is also great-ly reduced,making it easier either to use arraygain to suppress the spurious signal or to takeoffensive action against the jammer itself.Second, line-of-sight links lose much less oftheir signal strength to propagation losses anddata rates are therefore inherently higher, pro-viding the waveform designer with a higherbase to trade from in seeking to build in somejam resistance. And finally, because airborneplatforms are much cheaper than satellites, itis possible to create networks with manymore nodes, all within line-of-sight of eachother but arrayed along different azimuthsfrom any one jammer. Azimuth diversitycombined with packet switching couldenable an airborne communications networkthat resembled the terrestrial internet in thatit could experience a loss of the link betweenany two nodes and still allow them to com-municate with each other.

If one looks around the world, one can identify those few countries with serious air defenses by the presence of AEW

aircraft. At sea, the presence or absence of carrier-borne AEW is even more decisive.

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BECAUSE THE OTHER SERVICES arelikely to face political constraints ontheir access ashore early in future con-

flicts, the Navy will face greater demands onits power projection capabilities. But theNavy will also remain largely if not solelyresponsible for countering opposing accessdenial efforts at sea, both to ensure the secu-rity of its own base of operations, and toenable the safe entry and secure operation ofjoint, follow-on forces.

This section is organized in three parts. Itdiscusses the evolution of the demands onthe Navy’s access assurance capabilities dur-ing and since the end of the Cold War; thecurrent status of sensors, weapons, and net-works in this mission area; and future oppor-tunities for innovation in both technologyand doctrine by naval aviation.

The Cold War Legacy

The pillars of today’s and tomorrow’s SeaShield posture were laid during the ColdWar in the undersea and antiair warfare mis-sion areas. In these warfare areas, the Navyfaced an opponent whose prime focus wasthe denial of access by sea-based power pro-jection forces, and who chose what wouldnow be called asymmetric means in the pur-suit of that goal.

Undersea Warfare

Undersea warfare can be divided for ourpurposes into antisubmarine warfare andcounter-mine warfare. Both warfare areashave experienced dramatic change since the

end of the Cold War, but both remainimportant sources of sea denial leverage forfuture opponents. That is because modern,non-nuclear submarines and mines remainin some ways the ultimate conventional,asymmetric threats.They can do damage tomajor, high value naval platforms, yet theycan only be countered by an effort whosecost greatly exceeds that necessary to gener-ate the initial threat.Thus, they pose uniquechallenges in today’s security environmentbecause they remain one of the best ways tocause politically significant losses toAmerican or allied ships despite the dramat-ic diminution in the overall level of the ASWand mine threat compared to the Cold War.This often makes the case for better ASWand mine warfare capabilities both importantand difficult to make in today’s budgetaryenvironment.

ASW During the Cold War. After WorldWar II, Soviet submarines based on capturedGerman designs threatened to render obso-lete much of the U.S. Navy's ASW posture,which had been focused on dealing withsubmarines that lost a substantial portion oftheir offensive capabilities when forced tosubmerge. At the same time, the SovietUnion, being a continental power, threat-ened to make the U.S. Navy's victorioussubmarine force irrelevant, since submarineswere primarily useful as an anti-surfaceweapon against merchant shipping, and theSoviet Union could easily survive withoutmerchant shipping.

Out of this challenge grew two initiallyseparate innovations which, when brought

Sea Shield Past, Present, and Future

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together, formed one of the cornerstones ofthe U.S. Navy's Cold War ASW posture.

The first innovation involved the exploita-tion of passive acoustics to detect and tracksubmerged submarines, using the sounds theygenerated as a signature. Passive sonars signif-icantly increased the range at which sub-merged submarines could be detectedcompared to active sonar, allowing for verywide area searches by ocean-wide sound sur-veillance systems, which in turn could beused to accurately cue ASW platforms tolocalize and prosecute the submarine contact.The second innovation began with theembrace by the U.S. Navy's submarine andmaritime patrol communities of ASW as theirprimary Cold War missions, using passiveacoustics as their primary method for search,classification, and localization.

Maritime patrol aircraft offered speed thatsubmarines lacked, making them particularlyuseful in the initial localization of a contactprovided by offboard surveillance systems,which could then be handed off to a plat-form with more endurance, such as a nuclearsubmarine. The surface warfare communityremained dependent on active sonar until thelate 1970s.Then, in response to the deploy-ment of more capable Soviet submarine-launched antiship missiles, surface combatantsalso embraced passive acoustics and longrange, shipborne ASW helicopters.

By the early 1980s, all of the Navy's plat-form communities were being used success-fully in ASW operations against Sovietsubmarines, and increasingly these opera-tions demanded a high degree of coordina-tion as Soviet submarines became quieter.Earlier in the Cold War, when U.S. acousticsuperiority was still unchallenged, each plat-form community's ASW operations hadbeen relatively independent of each other.This independence reflected a natural divi-sion of labor based on the strengths and

weaknesses of each ASW platform. Thus,submarines went forward into contestedwaters where other ASW platforms couldnot operate, maritime patrol aircraft usedtheir speed to prosecute long range contactsgenerated by underwater surveillance sys-tems, and surface combatants utilized theirendurance to provide a local screen for bat-tlegroups and convoys.

The key to success in these relativelyuncoordinated operations was maintaining ahigh degree of acoustic superiority overSoviet submarines. Ironically, that superiori-ty began waning in the 1980s, just as theCold War was ending, in an echo of the endof World War II.This ending to what was thethird battle of the Atlantic was fortunate, butthe Navy will face new ASW challenges notunlike those it avoided when the SovietUnion collapsed, albeit on a smaller scale.

ASW After the Cold War. The threat toAmerican acoustic superiority resulting fromthe first Soviet deployments of the Akula inthe mid 1980s may recur in today's securityenvironment with the increasingly wide pro-liferation of modern non-nuclear sub-marines. Deployed relatively close to theirhomes, in or near littoral waters throughwhich the United States may need to projectpower from the sea, and where it is easier fora weaker Navy to obtain cueing informationagainst U.S. ships, these submarines pose apotentially formidable threat.With a compe-tent crew and the kind of advanced weaponsthat are now widely available in global armsmarkets, a modern non-nuclear submarinedeployed in its own backyard might becomea poor man's Akula. Of even more concern isthe fact that modern weapons, such as wakehoming torpedoes for example, tend toreduce the demands on submarine crews,making even less competent crews too dan-gerous to ignore.

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Modern non-nuclear submarines areboth better than those deployed by theSoviet Union during the Cold War, andmore widely available as defense industriesthat served their home markets during theCold War now use exports to stay alive. Onereason that the submarines are better isbecause many decades of continual invest-ment by countries like Germany andSweden have finally paid off in the form ofnon-nuclear submarines with both rafteddiesel propulsion plants that greatly reducetheir acoustic signature when snorkeling,and with air independent propulsion (AIP)systems that make them more like true sub-marines rather than mere submersibles.

These submarines still do not provide any-thing like the mobility and endurance of anuclear submarine, but they reduce the indis-cretion rate of a traditional diesel-electricsubmarine when on a slow speed patrol. Sucha submarine, patrolling in a limited area in ornear its home waters, would need to exposeits snorkeling mast much less frequently thando older versions of the Russian Kilo andwould be less vulnerable when it did.

Such submarines will also be armedwith better weapons and fire control sys-tems. One particularly alarming develop-ment is the marriage made possible by theend of the Cold War of the air indepen-dent, non-nuclear submarine with the sub-marine-launched antiship missile. Armedwith Harpoons or Exocets available fromseveral western suppliers, or Russian mis-siles like the Novator 3M-54E, these plat-forms can launch fire and forget missilesfrom over a surface ship’s radar horizonwithout the need for the noisy and battery-draining approach run necessary for a tradi-tional, torpedo-armed, diesel-electric boat.Absent high quality over-the-horizon cue-ing, these attacks will be prone to homingon the wrong target in a cluttered environ-

ment, but will be very hard to defendagainst in those cases where the weaponhomes on the right target. This threat cir-cumvents the traditional ASW approach todealing with very quiet diesel-electrics, i.e.to flood the ocean surface with radar anduse speed to force the submarine to eitherrun down its battery and expose itself in anattack run, or stay quiet and defensive.

There is also a political challenge associ-ated with conflicts in which the UnitedStates is fighting over less than all out stakes.In such conflicts, there will be a very lowtolerance for shipping losses, but the pres-ence of an opposing submarine force willput great pressure on the Navy if it mustrapidly project power and protect againstthose submarines at the same time.

Regarding casualties, even in a majorregional contingency, the stakes for theUnited States are limited while those of itsopponents are very high indeed.The oppo-nent may be willing to run great risks andsustain high losses, while the U.S. is less will-ing to do so. Faced with the possibility orthe reality of losses at sea, the Navy willneed to mount a major effort to eliminatethe threat of further losses. In order to beable to do this while still projecting its ownpower, the Navy will need to make ASW aless protracted and asset-intensive exercise.

A good analogy is to the great Scud huntof Desert Storm.Thousands of sorties werediverted over several weeks from the air warduring Desert Storm to hunt for SCUDs tolittle or no effect. From an ASW perspective,this experience is illuminating for bothoperational and political reasons.

Operationally, Scud hunting was likeASW using traditional methods against avery quiet target. A large area needed to besearched for objects that easily blended intothe background and only intermittentlyexposed themselves.Thus radar was used to

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flood SCUD operating areas, unattendedground sensors were also deployed, and air-craft were used to pounce on potential con-tacts. This was a protracted, extremely assetintensive endeavor, characterized by falsealarms, high weapon expenditures, and lowsuccess rates. In short, a SCUD launcher wasmost likely to reveal itself by successfullylaunching its weapon, just as sinking shipsare often the only reliable indication thatthere is a submarine in the neighborhood.

The political lessons of the SCUD huntalso apply to ASW.Before the war, the SCUDhad rightly been dismissed as a serious mili-tary threat, but once they began landing inIsrael, the political imperative to allocatescarce resources to at least appear to counterthis threat rapidly overwhelmed these narrowmilitary calculations.The same political pres-sures would be brought to bear on ASWforces facing active enemy submarines, butunlike the Iraqi Scuds, which were terrorweapons without much military utility, sub-marines are a serious military threat as well apolitical one. Therefore, it will be importantto avoid delays in containing the ASW threat,and an ensuing delay in the closure of Marineamphibians or Army sealift ships.

A delay of several weeks during the haltingphase of a major contingency might not be awar stopper all by itself, but it is important tounderstand the consequences for current timephased force deployment list (TPFDL) time-lines, which assume closure of millions ofsquare feet of pre-positioned sealift within thefirst two weeks of the start of an MRC.Thiswould transform a rapid deployment into aslow one, throw the deployment timelines ofall the services askew, and open a window ofindeterminate size at the outset of a conflict inwhich the enemy can operate unmolestedexcept by those opposing forces already in the-ater, assuming they do not need an open sealine of communication to sustain themselves.

ASW will also be the primary tool forprotecting merchant fleets if and whenattacks against them are launched by anopponent seeking to coerce a third countryby attacking it commercial shipping. Thecapability to assure the protection of itscommercial shipping will probably be thesingle most important kind of security guar-antee that the United States will be able tooffer medium-sized powers along the Indo-Pacific littoral, because it is likely that sub-marine-based threats to that shipping will bethe primary source of leverage deployed byany would be hegemon in the region. Thisargument applies with particular force tothose countries dependent on externalsources of energy that are shipped by sea.

There is also a doctrinal challenge theNavy faces as it attempts to increase its abil-ity to project power from the sea.The Navyfaces a new operating environment in whichit is increasingly relevant and therefore indemand. Unlike in the post WWII era whenthe Navy was searching for a mission, it hasbeen inundated with new missions in thepost Cold War era, and these new missionscompete with ASW for resources.

This has serious consequences for ASWbecause, as noted above,ASW is a multi-plat-form mission area performed by multi-mis-sion platforms. As the Navy’s strike warfare,anti-air warfare, missile defense, andamphibious warfare capabilities have grownin importance in the nation’s military strate-gy, the Navy has shifted its focus away froman emphasis on blue water sea controltoward power projection and land control inthe littorals.Yet these missions must be per-formed by the same platforms that will per-form ASW in the littorals - the air, surface,and submarine communities, all supportedby the ocean surveillance community.

This “multi-mission pull” increasinglymakes ASW compete with strike warfare

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and theater air and missile defense for thesame resources and training opportunities.This shift in orientation is occurring at atime when technology increasingly demandsthat ASW be a coordinated, “combinedarms” exercise if it is to succeed.All elementsof the Navy’s ASW posture must be main-tained to succeed in the fight against quietsubmarines, but all three of the Navy’s majorplatform communities also face pressures toimprove the capabilities of their multimis-sion platforms in other mission areas.

Mine Warfare During and After theCold War. Counter-mine warfare in today’ssecurity environment shares much in com-mon with ASW, but is also unique in severalrespects. Like modern non-nuclear sub-marines operating on battery, mines can notbe detected at operationally significantranges using passive sonar, and they “oper-ate” in a shallow, cluttered environment inwhich their small size and ability to remainstill while retaining operational effectivenessall conspire to make detection and classifica-tion with active sonar extremely difficult.Likewise, in their effects, they also pose thesame kind of asymmetric threat in opera-tions where the U.S. Navy and its allies mustlimit ship losses to very low levels.

Like submarine-launched torpedoes,mines attack ships under their waterlinewhich makes them extremely lethal, butunlike submarines, mines lack mobility.Thuseven more then submarines, mines are onlyeffective when used in confined waters orchokepoints, and most mines also require rel-atively shallow water.Thus, mines have alwayshad particular utility when used to limit pas-sage to and from ports, to limit the operationof ships in shallow coastal waters or straits, andto frustrate or delay amphibious assaults.

All of these potential uses for mines havebeen of historic concern for the U.S. Navy,

but during the Cold War its counter mineposture was determined largely by a smallsubset of this threat. First, traditionalamphibious assaults was not considered like-ly in a major war with the Soviet Union, andthough the Navy and the Marine Corpsretained capabilities to clear mines in theapproaches to a landing beach, the require-ments in this mission area were set at the rel-atively low level expected in lessercontingencies. Second, the U.S. Navy’s mainoperational focus during the Cold War lay incountering the Soviet Navy’s expectedattempts to contest control of the Atlanticand Pacific sea lines of communications(SLOCs). In this blue water environment,mines were a minor factor. Certainly therewere ports at both ends of these SLOCs, andthere were also shallow, enclosed seas like theBaltic and Yellow Seas which would havebeen contested, but here Allied navies borethe brunt of the counter-mine burden. Themain exception to this division of labor lay inthe need for the U.S. Navy to assure access toports in the United States. For this purpose,the Navy developed and maintained a dedi-cated, U.S.-based Mine Countermeasure(MCM) force.

Desert Shield illustrated two weaknessesin this posture. First, early arriving navalforces lacked the organic MCM capabilitiesneeded in the event of an aggressive Iraqimine laying effort in the shallow waters ofthe Persian Gulf. In the event, a relativelysmall and incompetent Iraqi mine layingeffort led to two major ship casualties.Second, even after dedicated MCM forcesarrived in the Gulf after several months,these forces could not clear the extensivemine defenses the Iraqis had prepared alongthe Kuwaiti coastline with sufficient confi-dence to enable an amphibious assault.

This experience highlighted the newMCM challenges presented by the new

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security environment. First, CONUS-based,dedicated MCM forces can not deploy fastenough to support a forward deployed Navythat must confidently operate in littoralwaters early in a conflict, so those forwarddeployed forces must have organic MCMcapabilities that at least allow them to find,identify, and evade mines that would other-wise limit its access. Second, a serious min-ing effort by a competent adversary usingmodern mines will demand MCM capabili-ties based on new technology not resident inexisting MCM forces.

This challenge will be most serious intwo specific scenarios where mines canextract the greatest leverage; in deterringamphibious assaults against prepared coastaldefenses, and in delaying or interdicting thedeployment and sustainment of land-basedforces by mining the ports of debarkation towhich their sealift must have timely andunimpeded access. In the second of thesescenarios, the ASW and MCM challengesmay merge, as the submarine may be theonly mining platform available to a weakerpower seeking to operate in an opponent’shome waters. In both cases, the U.S. Navy’schallenge is to enable power projection andsustainment by joint forces, and to protectcommercial shipping routes.

Antiair Warfare

As with undersea warfare, elements of theU.S. Navy’s current antiair warfare (AAW)posture can be traced back to its experiencein World War II.Today’s antiship cruise mis-sile threat is the descendant of the Kamikazethreat and has traditionally represented theprimary above-the-waterline access con-straint for naval surface combatants. Non-nuclear, land-based ballistic missiles have nottraditionally posed threats to ships at sea, butcould in the future if more advanced adver-

saries can both deploy long range sea sur-veillance systems and maneuvering reentryvehicles with effective terminal sensors.GPS-guided ballistic and cruise missiles canalready now pose threats to bases ashore.Thus, the Navy will both need to defenditself at sea against cruise missiles and, per-haps, ballistic missiles, and also project adefense against such weapons ashore.

Antiship Missile Defense During theCold War. During World War II, the inte-grated air defenses contained within CarrierTask Forces became quite effective againstJapanese dive bombers and torpedo bombersfor two reasons. First, they projected thedefense outward such that many Japaneseaircraft never delivered their weapons, andsecond, their inner or terminal defensesgreatly reduced the effectiveness of weaponsthat were delivered by deterring mostJapanese pilots from flying the delivery pro-files necessary to give the short-ranged andunguided antiship weapons of the day theaccuracy needed to strike a maneuveringship with reasonable probability.

During the last year of the war, two newAAW challenges presented themselves. First,the Navy’s Carrier Task Forces switchedfrom pursuing the by then defeated Japanesefleet to supporting amphibious assaultsbeyond the range of land-based, tactical air-craft. This fixed carrier operations in spaceand time, making their movements moreconfined and predictable, and thereforemaking them easier for opposing, land-basedair forces to find. Furthermore, this limita-tion on the carriers’ ability to use movementand deception to frustrate Japanese airattacks lasted for the weeks or months that ittook to build up land-based aviation ashore.

Second, it was also at this point that theJapanese introduced the Kamikaze tactic.The challenge posed by Kamikaze aircraft

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was that their pilots were no longerdeterred by a Task Force’s terminal defens-es, making the platforms they were pilotinginto very intelligent missiles that wereguided all the way to their targets. Theseaircraft had no better luck than their non-Kamikaze counterparts penetrating a taskforce’s outer defenses, but those that didpenetrate were much more lethal. Thus,Carrier Task Forces became easier to findbecause they were tethered to the shore foran extended period, and their terminaldefenses were less effective against guidedweapons that could not be deterred frompressing home their attacks.

During the Cold War, the evolution of theantiship missile threat went through threephases corresponding to the years when theCarrier Battle Group was expected to be aprimary nuclear delivery platform against theSoviet Union (roughly 1948-1960), the yearswhen Battle Groups were focused on pro-jecting power in limited conflicts in the thirdworld (roughly 1960-1975), and the yearswhen Battle Groups refocused on operationsagainst the Soviet Union, albeit in a primar-ily conventional rather than a nuclear role(roughly 1975-1990).

During the first phase, the Soviet Navydeployed radar-guided missiles in both airand submarine-launched versions that weredesigned to defend Soviet territory fromcarrier-based nuclear strikes. Launched fromfaster, higher flying, radar-equipped jet air-craft like the Badger, these air-launched mis-siles posed a day or night, all weather threatto the carriers which could not be coun-tered by traditional air defense systems.Attacking jet aircraft approached the carriertoo high and fast for reactive, deck-launchedintercepts to be effective, while the tactic ofhaving a continuous combat air patrol in theair above the carrier was infeasible using theNavy’s early jet interceptors, which had low

endurance and were not yet truly night/allweather platforms. Furthermore, antiaircraftguns were almost completely ineffectiveagainst antiship missiles with jet and laterrocket motors.

Out of this threat grew several majorinnovations which have become keystonesof any modern integrated air defense system.Carrier-based airborne warning and controlaircraft with powerful radars were developedand deployed which greatly extended theouter ring of a Battle Group’s defenses byproviding much more warning of attack.Radar-guided surface-to-air missiles (SAMs)were developed and deployed. SAMs greatlyincreased the reach and effectiveness of anindividual ship’s defenses. Ships so equippedprovided true night/all weather air defensecapability, and with a family of missiles ofvarying size and range–the so-called 3-Ts:Terrier,Tartar, and Talos; these ships also con-tributed to both the outer and inner defens-es of a Battle Group.

A less visible but equally important inno-vation of this period was the developmentand deployment of the Naval Tactical DataSystem (NTDS). NTDS was the first widely-used digital data link and it grew out of theneed to integrate the Battle Group’s airdefense systems in a period when the speedand complexity of AAW operations hadexceeded the capacity of voice radio linksand yeomen with grease pencils writingbackwards on glass tracking boards.

Thus began a classic measure/counter-measure race between Navy fleet air defensesystems and Soviet antiship systems. SovietASMs grew faster and developed longer legs,forcing the Navy to further extend the outerrings of its Battle Groups’ air defenses, and toimprove its SAM-based inner rings. It was atthis point that E-2 warning aircraft and F-4interceptors armed with radar guided air-to-air missiles became the mainstay of the Battle

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Group’s outer ring of air defenses.The needto stand off from greater distances forced theSoviet Navy to improve its ocean surveil-lance and over-the-horizon targeting capa-bilities, which in turn led the Navy to placeincreasing emphasis on evading, spoofing, ordestroying those systems.

This race abated somewhat during theVietnam years when the Navy’s BattleGroups were focused on power projectionoperations in Southeast Asia, but renewedwith a vengeance during the third phase ofCold War AAW operations. The Navyemerged from the Vietnam years facing aSoviet Navy armed with a space-basedocean surveillance system that used radarand ELINT satellites to find and identifyU.S. ships, and provide over-the-horizon tar-geting information to long range SovietNaval Aviation (SNA) and nuclear poweredcruise missile submarines (SSGNs). Launchplatforms like the Backfire and the Oscarwere armed with supersonic antiship missilesof 100-300 mile range. From this distance,SNA bombers and SSGNs sought to launchmissiles from outside a Battle Group’s outerdefenses, thus saturating its inner defenseswith multiple incoming missiles.

Out of this challenge grew the AAWposture designed to enable the forwardBattle Group operations envisaged by theMaritime Strategy of the 1980s. E-2s andF-14s armed with long range PhoenixAAMs extended the Battle Group’s outerring. As important, aggressive efforts weremounted to provide strategic as well as tac-tical warning to the Battle Group of animpending SNA attack. Out of this partic-ular initiative grew some of the first andmost successful tactical exploitations ofnational capabilities (TENCAP), includinga program which used missile early warningsystems to detect and track the exhaustplumes of Soviet naval aviation aircraft in

flight. Linked together by real time datalinks, these assets collectively extended theouter air battle hundreds of miles from theBattle Group, reestablishing a robust barrierthat SNA needed to penetrate before itcould launch its missiles.

At the same time, the Aegis weapon sys-tem was deployed during this period. Aegisvastly expanded the capabilities of the Navy’sair defense cruisers to deal with antiship mis-siles that leaked through a Battle Group’souter ring. Its phased array radar could trackhundreds rather than tens of targets simulta-neously, and its target illuminators couldguide up to 16 SAMs simultaneously, ratherthan one or two. Furthermore, becauseSoviet antiship missiles flew high altitude,arcing profiles in order to extend their range,Aegis could see them at great distances, andbecause of the speed with which Aegis couldprosecute individual engagements, it couldget off multiple shots against the same mis-sile raid.

In addition to Aegis and the Outer AirBattle, the Navy aggressively pursued mea-sures to counter Soviet ocean surveillancesystems at the front end of the engagementcycle, as well as a panoply of close in systemsdesigned to give each Battle Group combat-ant the ability to defend against antiship mis-siles in their terminal phase.

Soviet ocean surveillance systems, whichby the 1970s included a substantial space-based component, provide an example of thekind of space capabilities that future adver-saries might deploy. It’s photo satellites,ELINT satellites, and radar satellites usedtechnology that was quite advanced for thetime, including systems designed to geolo-cate electronic emissions from space, and touse synthetic aperture techniques to distin-guish between specific ship types. And theU.S. Navy’s response to this system is alsoinstructive, including a reporting system that

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told ships when Soviet satellites were over-head, emission control tactics which deniedELINT satellites a signal to exploit, or falseemitter tactics which put an emitter normal-ly associated with a specific platform on adecoy platform.

One indication of the success of thesecountermeasures is the fact that the Sovietswere never able to reduce their reliance onmaritime patrol aircraft such as the Bear,which of course were quite vulnerable to acarrier’s outer air defenses. It is important tokeep this experience in mind for the future,because it demonstrates that the meredemonstration of space capability by a futureopponent, even a very ambitious one likethe Soviets deployed during the Cold War,will not necessarily translate into an effectiveocean surveillance system

The Navy was also aggressive in improv-ing terminal defenses during this period. Inthis category were systems like the Close InWeapons System (CIWS), a self-contained,radar-cued gatling gun designed to detectand attack incoming missiles automaticallyas they approached individual ships. Also,because Soviet antiship missiles were guidedby small aperture radars in their terminalphase, decoys and jammers were deployed toeither fool or blind those radars when theywent active. In this context, the Navy alsobegan to reduce the radar cross section of itsships, not to defeat Soviet surveillanceefforts, but to enhance the effectiveness ofdecoys and jammers used against missilehoming radars.

Antiship Missile Defense After the ColdWar. In the new security environment, theAAW threat has changed in at least fourbasic ways. First, the days of large, saturationmissile attacks launched at long range byplatforms with an ocean-wide reach areover. In that sense, the antiship threat has

declined dramatically. Second, on the otherhand, the U.S. Navy aspires to a much moreaggressive power projection posture than itdid during the Cold War. For example, intoday’s security environment, in an analogueto what happened in the Pacific duringWWII after the Japanese fleet was defeated,Battle Groups are expected to conduct pro-tracted, high volume strike operations with-in 200 miles of an enemy coast. Surfacecombatants will be expected to providenaval surface fire support to engagedMarines ashore from just over the horizon ofan enemy coastline.Third, for the foreseeablefuture, these operations will likely occur incrises or conflicts where there is a greatasymmetry in the stakes in the outcomeamong the contestants favoring the UnitedStates’ opponent.This will continue to makeU.S. military and political leaders averse tohuman and material loss among its forces.And fourth, “export or die,” post Cold Wararms export markets will continue to pro-vide potential U.S. opponents with modernsea skimming, antiship cruise missiles.A fifthchange may involve the development ofland-based ballistic missiles with an anti-shipcapability.

This environment has already caused afundamental shift in the Navy’s AAW pos-ture, and this posture will need to continueevolving to stay abreast of this threat. Theessence of this threat today and in the nearfuture is the specter of supersonic, sea skim-ming ASCM attacks in the littoral launchedfrom truck-mounted launchers ashore, fastboats, or non-nuclear submarines whichevade a Battle Group’s ASW screen. Suchattacks would give individual ship terminaldefenses only minutes to detect and attackincoming missiles as they break the radarhorizon at a distance of only 15-20 miles.This threat is already ubiquitous today inthose operational scenarios where ships must

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approach within line-of sight of a hostilecoastline. Coming this close essentiallysolves the opponent’s surveillance problem,and provides sufficient targeting informationto launch truck-mounted, ASCMs down abearing along which lies a U.S. surface com-batant within 20-25 miles.

In order to extend this threat outwardthe 200-300 miles necessary to sharplylimit Battle Group operations, the oppo-nent will need to extend its view of the lit-toral battlespace by moving its surveillanceassets upwards, and to extend the reach ofits ASM platforms without thereby re-exposing them to a Battle Group’s outerdefenses. In assessing how potential oppo-nents will grapple with this challenge, it isessential to be clear about the problemsthey will face.

The most important issue is the distinc-tion between a wartime capability and onethat functions effectively only in peacetimeor a crisis.Wide area surveillance of the oceansurface requires putting sensors within rela-tively continuous line-of-sight of the area tobe surveilled. In the case of any near termopponent, these sensors will need to bedeployed in airspace that will be contestedduring a war. Certainly in the near term, theUnited States will win those contests whenan opponent seeks to operate well outside itsown airspace.Thus, it will be very difficult forsome time for potential U.S. opponents todevelop and deploy a robust, dedicated,ocean-wide or even littoral-wide surveillancesystem for use in wartime against U.S. navalforces.

Much more feasible is a system that seeksonly to preserve the wartime reach of sur-veillance assets out to the “electronic hori-zon” of the littoral battlespace as viewedfrom the opponent’s coastline. Depending onthe range and elevation of the sensors used,the highly contested littoral battlespace in

wartime would extend for at least 20-25miles, and its outer limits would roughly cor-respond to the 200-300 mile radius limit forcurrent, high volume carrier strike opera-tions. Outside that radius, an opponent’s viewwould be limited to peacetime or crisis oper-ations in which vulnerable assets like longrange patrol aircraft are able to operatebecause the rules of engagement do notallow U.S. attacks against them. This wouldenable an opponent to cue ASCM-equippedsurface combatants with the speed andendurance to trail Battle Groups, providing alimited but potentially effective “first salvo”capability much like that pursued by other-wise vulnerable Soviet surface ships in theMediterranean during the 1973 Yom KippurWar. But such a wide area system would notbe effective against Battle Groups which sur-vived or were not-exposed to the first salvo.

Inside a 200-300 mile radius, early in aconflict, Navy surface combatants will facethe prospect of ASCM attacks launched fromland, submarines, or small, fast boats, andcued by elevated, offboard sensors. The ele-vated offboard sensors, whether aircraft,UAVs, or aerostats, and their command, con-trol, and processing facilities will be protect-ed by modern, mobile SAMs able to reachsome 50-100 miles outward from the oppo-nent’s coast, and at elevations of 50-60,000feet, these sensors will have an horizonstretching some 200 miles. A further stepupward in the opponent’s anti-access capabil-ity will occur within 20-25 miles of its coast.Within this region of the littoral, an oppo-nent’s ASCM missiles will not need offboardcueing to be effective, and the opponent’sASCM launchers will be operating in a highclutter environment in which it will be muchmore difficult for the Battle Group to inter-dict or suppress these launchers before theylaunch their missiles. In this environment,extreme pressure will be placed on the inter-

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mediate and terminal ASCM defenses of theships comprising a Battle Group.

Thus, the near to mid term antiship mis-sile defense challenge will likely resolve itselfinto three elements corresponding to thesurvivability of the opponent’s surveillancecapabilities: the opponent’s peacetime sur-veillance system that gives extended reachbut is vulnerable; it’s extended littoral systemwhich reaches out 200-300 miles and whoseairborne sensors can survive as long as themodern, mobile SAMs that protect it remainunsuppressed; and its core wartime systemwhich is limited to the 20-25 mile horizonfrom the opponent’s own coastline.

It is important to note again that themost serious access challenge faced by theNavy in this area comes when it is playingthe role of an enabling force for the otherservices. Thus, for example, Battle Groupsstanding off more than 300 hundred milesfrom an opponent’s coast can still launchTomahawk missiles and long range aircraftstrikes essentially at will once an opponent’speacetime surveillance system has beendestroyed, albeit at a lower sortie rate thanwhen such operations are mounted over ashorter radius of operation. But naval com-batants will have to close within 20-25 milesof a hostile shore to provide the naval firesthat will enable ship to objective maneuver(STOM) by Marine Expeditionary Units(MEUs), and MEUs will often be the key togaining access to the ports and airfieldsashore that are necessary for reinforcingground and air units.

Sensors, Weapons, andNetworks for Gaining andExploiting Access

The need to gain and exploit access in thenew security environment will drive theNavy toward better sensors and weapons,

and toward networks that link them togeth-er and process their output more effectively.There are both immediate opportunities inthis regard, and opportunities which demandfurther development. This section will lookat the immediate naval aviation opportuni-ties in the Sea Shield mission area that arealready being pursued.

Countering Submarines andMines

The ASW and Mine Countermeasure prob-lem in the littorals will always be difficult.But tremendous progress has been made inthe ten years since the end of the Cold Waron the main challenges in these areas.Compared to other warfare areas, ASW andMCM pose particular challenges in the areasof sensors and, to a slightly lesser extent,weapons. Networks are very important inASW, but the networking technology need-ed is less demanding in many ways than thenetworking requirements in AAW. Networksare less important to MCM.

ASW Surveillance Sensors. The primaryASW challenge has always been wide areasurveillance or search, and the main chal-lenge initially posed by the new securityenvironment in this mission area is a widearea search problem. Sound propagates bet-ter in deep water than in shallow water, andnon-nuclear submarines can remain silentfor extended periods when allowed to patrolsmall areas near their home ports at lowspeed. Using passive acoustics to search forsuch submarines is much more difficult thanit was to search for relatively loud Sovietsubmarines operating in deep water duringthe Cold War. On the other hand, activesonars encounter serious problems withclutter in shallow water, much as early radarsdid when forced to look down at targets fly-

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ing over land.And even in shallow water, thewater column still remains relatively opaqueto non-acoustic energy, limiting the role ofRF and laser radars as long range sensors.

Three systems stand out as first stepstoward regaining a wide area search capabil-ity in the littorals. The first is called theAdvanced Deployable System (ADS); thesecond, derived from the Distant Thunderexperiment, is Advanced Explosive EchoRanging (AEER); and the third is the LowFrequency Active (LFA) variant of theSurveillance Towed Array Sensor System(SURTASS).ADS is a passive ocean bottomarray that can be deployed by a surface ship,and whose output is currently collected andprocessed ashore via fiber-optic cable.AEER is primarily a signal processingadjunct to existing ASW combat systems,combined with coherent, air-droppable,active sound sources and a relatively simpledata link that uses existing UHF radios onparticipating platforms. LFA is a very power-ful, low frequency active sonar.

Unlike the Cold War Sound SurveillanceSystem (SOSUS) arrays, which listened forlow frequency, narrow band tonals propagat-ing outward horizontally along the deepsound channel, nodes in an ADS array lookupward along what is called the ReliableAcoustic Path (RAP). ADS is a derivative ofthe Cold War Fixed Distributed System (FDS)program, which was an attempt to repair theASW barrier strategy by using many simplepassive sensors in an upward looking array thatused the reliable acoustic path (essentially thedirect path) rather than the deep sound chan-nel. Each sensor would cover a small cone ofthe ocean column, and fiber optic cable pro-vided the bandwidth to network a vast arrayof these small sensors and bring their outputashore for processing. Future work on ADSwill focus on deploying the arrays covertly viasubmarine, protecting the arrays from bottom

trawlers, and using buoys to relay the arrayoutput directly to ships at sea.

AEER adds commercial off the shelf(COTS) processing to existing towed arrayson ships (and potentially, submarines) andair-deployed sonobuoys, and links theprocessors together using legacy radios withmodems to form a network that can dobistatic or multistatic processing of theechoes from the air-dropped sound source.The essence of AEER is that it uses bothspatial and temporal processing to extract asubmarine’s echo from the clutter and rever-beration. Long wavelength towed arrays ordirectional sonobuoys use spatial processingto eliminate clutter and reverberation excepton the azimuth of interest, and temporal pro-cessing allows reverberating echoes from thesame object to be compared over time,thereby exploiting the fact that a submarine’secho loses less of its higher frequency spec-trum in that time than do objects sitting onthe bottom or floating on the surface.

One of the original concerns from DistantThunder was that variations in bottom topog-raphy and content would interfere withAEER’s temporal processing capability, butworldwide experiments have demonstratedexcellent performance over a wide range ofenvironments. Like all acoustic sensors, perfor-mance will vary in practice depending onmany circumstances, but AEER will significantimprove the detection ranges achieved usingactive sonar in the cluttered shallow waterASW environment. Another benefit of AEERis that it demonstrates long range performanceunder a wide variety of acoustic conditions,including the very common case in the littoralwhere sound is refracted away from the surface,a condition which drastically reduces the per-formance of a traditional, hull-mounted sonar.The main challenge facing AEER today is thatits recognition differential is low when used bynon-laboratory personnel.

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Finally, both ADS and AEER are alsogreat examples of the incredible power ofnetworked sensors, and the relative ease ofbackfitting such a capability onto legacyplatforms once the substantial initial chal-lenge of developing the necessary signal pro-cessing algorithms is completed. Systems likeAEER can be backfitted onto any towedarray ship or submarine, and onto LAMPshelos and P-3s.

SURTASS was a late Cold War systemthat used towed passive acoustic arrays tosupplement SOSUS coverage, or extendcoverage into waters too shallow for a deepsound channel. SURTASS has been upgrad-ed with better passive acoustic capabilities,and LFA is an additional update that adds anactive, low frequency acoustic source, trans-forming SURTASS into an active sonar.

Specialized periscope or mast detectionradars can also play an important role in theASW search problem. Even during the ColdWar, Soviet nuclear submarines regularlyexposed a periscope when seeking a torpedofire control solution against the fast ships of aBattle Group. And of course radar has animportant role to play in preventing dieselsubmarines from snorkeling to recharge theirbatteries. Thus, a combination of speed, andradar deployed to search within the limitinglines of approach created by that speed, havealways been an important ASW tactic againstall submarines. Likewise, radar flooding inwhich a large area is flooded with RF ener-gy so as to set off a submarine’s radar warn-ing alarm whenever it exposes a mast is alsoa traditional tactic against diesel submarines.But specialized mast detection radars like theAPS-137 experience tremendous false alarmrates caused by both sea state and other float-ing objects and debris when their detectionthreshold is set low to maximize range.

The Automatic Radar PeriscopeDetection and Discrimination (ARPDD)

program is developing the capability toprocess APS-137 returns in such a way as toallow very low detection thresholds (i.e. longrange) and very low false alarm rates. Veryimpressive results have already been demon-strated in shipboard experiments, but unlikesystems like AEER, ARPDD needs furtherdevelopment time to reduce the footprint ofthe massive processing capability it nowrequires before it can be deployed on surfaceships, maritime patrol aircraft, or helicopters.

Maritime Patrol Aircraft and Helicopters.Long range, persistent, land-based maritimepatrol aircraft provide the only way for adominant naval power to maintain a continu-ous presence and surveillance throughout thevast ocean and littoral spaces over which itmust exercise control.They often provide themost timely means of response, whether to afleeting undersea acoustic contact, a report ofa suspicious merchant ship, or an importantsignals intelligence collection opportunity.

In ASW, because sensor performance islimited, detection ranges are reduced, mak-ing wide area surveillance a more asset-intensive endeavor. Furthermore, all but thevery quietest nuclear submarines, produce acontinuous acoustic signature, whereas thebest detection opportunities against non-nuclear submarines are both episodic and dif-ficult to classify. On the other hand, there is aclose correlation between the steps a subma-rine needs to take in order get into positionto attack a target, and the operational indis-cretions which provide the best detectionopportunities for ASW forces. Therefore,contacts must be prosecuted and reliably clas-sified as quickly as possible before they disap-pear back into the cluttered background as anunknown contact. This puts a premium onASW platforms that can be deployed in num-bers and distributed throughout the sea base,close a potential contact quickly, and deploy a

Among many roles, maritime patrol aircraft and multi-mission helicopters will provide the best means of making opposing

submarines pay for their inevitable indiscretions.

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menu of high quality acoustic and non-acoustic sensors to reacquire and identify thecontact, classifying it as a false alarm, or trail-ing and/or attacking it.

Multimission maritime patrol aircraft andship-based helicopters will play an increas-ingly important ASW role in the new secu-rity environment because they provide thebest means of quickly responding to surveil-lance cues, especially when those cues donot include reliable classification of the tar-get, as they often will not.

ASW Weapons.Torpedoes remain the pri-mary ASW weapon in the littoral environ-ment, although this environment alsopresents them with great challenges, partic-ularly lightweight torpedoes, which are “fireand forget” weapons. Like all fire and forgetweapons, the relatively small aperture andlimited signal processing available to a light-weight torpedo’s active seeker makes forproblems in shallow water where there is alot of clutter and the target is relatively smalland moving slowly. The Mk. 50 modifica-tion to the Mk. 46 lightweight torpedo pro-vides an initial response to this problem, andthe more ambitious Mk. 54 a more robustresponse in a few years.

There is also an alternative ASW weaponopportunity that grows out of the intersec-tion between MCM and ASW. One of thechallenges in the organic MCM program isto do in stride mine neutralization andclearance from a helicopter, and the RapidAirborne Mine Clearance System (RAM-ICS) program’s approach to this problemmay provide another ASW weapon oppor-tunity as well. RAMICS is discussed inmore detail below.

A Common ASW Operational Picture.One of the legacies of the formidable passiveacoustic detection ranges possible in ASW

during the Cold War is the tradition of rela-tively autonomous operation amongst theNavy’s main ASW platforms.When the SovietNavy finally deployed very quiet nuclear sub-marines near the end of the Cold War, theneed for more coordination arose. Today,coordination is even more important, espe-cially to give the ASW commander and all ofhis forces a wide area picture of the ASW bat-tlefield. Such a picture would allow better uti-lization of multiple, often evanescent contactsagainst the same target produced by differentsensors; it would give units knowledge ofenvironmental conditions over a wide area,allowing them to better predict the perfor-mance of their sensors as they move about thebattlefield; and it would identify resulting“holes” in ASW coverage where search assetscould be concentrated efficiently.

Most of the individual pieces of workneeded to accomplish this task are relativelysimple, such as using common operationalprotocols when processing and communi-cating data, and using the same environmen-tal models. But the task is complicated bythe need to integrate these activities acrossmany platforms.

MCM Sensors. As with ASW, sensor per-formance is central to success.And again, thebeginning of the problem is always to detectand identify the mines in the first place. Inthe new security environment, this challengeis further complicated by the need to makesuch a mine hunting capability organic to theNavy’s forward deployed Carrier StrikeGroups, Expeditionary Strike Groups, andSubmarines.

The key opportunities in this areabeing exploited today are very compact,imaging sonars and laser radars (LIDARS)able to detect and identify mines in thewater column and on the bottom.Because these sensors can be made very

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small, they can be deployed on or towedby smaller helicopters such as the CH-60; put on a surface ship-launched andcontrolled, semi-submersible vehicle; oreven inside a torpedo-sized UUVlaunched and recovered from a subma-rine. Through the regular, peacetimeemployment of these sensors, the Navycan map the ocean bottom, particularlynear key approaches or chokepoints.Doing so will facilitate the location ofnewly-placed mines, appearing as“deltas” from the peacetime picture,allowing forward deployed forces torapidly focus on areas to avoid, or if theyare critical, areas to clear. The uniqueadvantage of the submarine-UUV com-bination is that this sensing can occurregularly without raising suspicion.

MCM Weapons. Once identified, minesneed to be neutralized or destroyed. Inmany cases, the instruments that accomplishthis purpose are not really weapons, but socalled influence devices designed to createthe signature needed to set off the mine ina way that does not destroy the minesweeping platform. An influence sweepusually requires a platform that will notitself set off the mine, but which can tow avehicle that will, hence the long tradition ofrelatively small, dedicated minesweepingships with low magnetic and acoustic signa-tures. More recently, helicopters have beenemployed to tow influence sleds, but thesize of the latter has required the towingservices of heavy lift helicopters like themassive CH-53. Some of the same trendswhich will allow smaller MCM sensors willalso allow smaller influence sleds, enablingan eventual transition to a CH-60 platform,and in turn allowing forward deploymenton existing carriers, surface combatants, andamphibious ships.

In addition to influence sweeps, MCMforces also must have the ability to individu-ally approach and remove or destroy all themines it has found, because influence sweepstrade off speed for a reduced certainty that aminefield has been truly cleared. Here, oneencounters perhaps the slowest and mostlabor intensive naval warfare area, in whichtoday’s dedicated MCM force utilizes explo-sive ordnance disposal (EOD) divers, marinemammal systems (MMS), and remotelyoperated underwater vehicles.

New approaches to this problem designedfor use by organic MCM forces focus onhelicopter-deployed systems. In the nearerterm, a helicopter-delivered, remotely oper-ated underwater vehicle will be deployedthat can approach an already identified mineand explosively destroy both itself and themine. In the longer term, the RAMICS sys-tem described above is being developed.RAMICS will combine a LIDAR and aGatling gun firing supercavitating, 20mmprojectiles. The LIDAR would be used tosearch for and identify mines, and the gun’sprojectiles would disable or neutralize it bypenetrating the mine’s shell and injecting achemical initiator into it.

The MCM Network. Unlike sophisticatednetworks like AEER, and those that will bedescribed below for AAW and strike warfare,the main network in MCM is human, andthe center of this network is the dedicatedMCM force. This is to say that even morethan ASW, MCM success is not a science butan art that requires practice and extensive,detailed knowledge, and which is thereforeextremely perishable. A dedicated MCMforce is the home for this expertise, becauseit is the only place in the Navy where offi-cers will do nothing but train for MCM, andwhere the intelligence on foreign mines willbe sustained.

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Also, the nature of the entire underseawarfare threat, and particularly the minethreat, is that its most challenging manifes-tations have primarily “purple” and “green”consequences. In other words, an aggressive,inshore mining campaign by an opponentwill more directly impact the projection ofArmy and Marine Corps power than it willpurely naval power, and even when theNavy does face a serious mine threat, it willusually arise when it is operating in directsupport of the Marines, as in the NSFS mis-sion. Combined with an aggressive organicMCM program, this might lead some toadvocate the eventual dissolution of thededicated MCM force for narrow bud-getary purposes. A salutary warning of thelikely consequences of such a decision isprovided by the Air Force’s decision afterthe Gulf War to retire its dedicated airborneelectronic attack and air defense suppressionassets in the belief that stealth would makesuch a dedicated force unnecessary.

Countering Missiles

Throughout the Cold War, the main AAWthreat to U.S. Navy Battle Groups was thelong range, air and submarined-launched,antiship missile.This threat presented itself atgreat distances from the Soviet homeland,and was supported by an ocean wide surveil-lance system. The seriousness of this threatprovoked major attempts by the Navy to dealwith it at every step in the engagementsequence. Efforts were mounted to defeat orfool the surveillance system, to attack thelaunch platforms before they could launchtheir weapons, to take multiple shots at theweapons themselves if they leaked through abattle group’s outer defenses, and to defeatthe weapon’s seeker in the terminal phasewith both active and passive countermea-sures.All of these defensive measures required

depth, and depth was naturally provided inthis Cold War mission area by the great rangeat which Soviet sea denial operations againstU.S. Battle Groups were mounted.

The main problem with the littoral AAWthreat is that this depth is largely absent, bothbecause the U.S. Navy seeks to close with itsadversaries, and because those adversaries aregenerally constrained anyway to operationswithin the littoral battlespace. This meansthat an adversary’s launch platforms will beburied in the clutter and noise of the littoralenvironment, either on land or in shallowinshore waters where it is easy for them tohide. It also means that the surveillance sys-tem that cues those launchers need notapproach ocean-wide coverage, but rathermust only aspire to cover a radius of severalhundred miles outward from the coast. Andfinally, because ASCM weapon engagementswill usually occur over an even shorter rangewithin the contested littoral battlespace, thespecific weapons used can be relatively shortrange, sea skimming missiles rather than thehigh arcing AS-6s and SS-N-19s of ColdWar fame.

All of these factors conspire to radicallycompress an AAW engagement in space andtime, reducing the role of the outer air bat-tle, and reducing the number of shots avail-able during the inner air battle. For the mostserious sea skimming ASCM threats,launched from platforms that have success-fully approached a Battle Group in the lit-toral clutter, the AAW engagement willbegin when the attacking missile approach-es the targeted ship’s radar horizon—say 20miles—and will be over, for better or worse,within one or two minutes.

Three interrelated steps are being taken tocounter this threat. First, elevated sensorsneed to be developed which can eliminate orgreatly reduce the clutter in the littoral envi-ronment which allows ASCM launchers to

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hide, and which also prevents missile detec-tion until the terminal phase of an engage-ment. Second, weapons need to be developedthat can function in the same cluttered envi-ronment against small, fast targets. And third,these sensors and weapons need to be linkedtogether in such a way as to allow an elevatedsensor to provide the information needed foranother platform to launch a defensiveweapon against the incoming weapon fromover the radar horizon.

Advanced Hawkeye Will Reduce LittoralClutter. Central to the ASCM defenseproblem is a much better wide area picture ofthe littoral air space, particularly at the lowaltitudes relevant to the ASCM problem.TheE-2 is the Navy’s primary AAW surveillancesystem but it is not currently well equippedfor this task. As a relatively low frequency,pure pulsed UHF radar, the existing E-2 APS-145 radar has tremendous difficulty detectingtargets in the littoral for two basic reasons.

First, more than higher frequency, pulsedoppler radars like that on the Air Force’s E-3, the E-2 has trouble picking out low flyingtargets over land or among maritime clutterbecause it does not exploit Doppler signalprocessing.This was not a problem in a bluewater environment because at UHF the seasurface is a mirror, but in the littoral or overland, clutter interferes with the ability todetect low flying targets. And even radarsthat do use Doppler signal processing havetrouble with so-called low doppler targets.Alow doppler target is one whose movementrelative to the clutter background in thedirection of the surveillance radar is low,either because the target is moving slowly inabsolute terms, or because its direction ofmovement is perpendicular or nearly per-pendicular to that of the radar’s main beam.Historically, doppler signal processing inlook down radars has been most effective

against relatively high doppler targets, i.e.ones closing on the main beam of the radarat a relatively high rate. An ability to tracklow doppler targets in the littorals is criticalbecause both surface ships and aircraft, aswell as ASCMs, will often present them-selves as low doppler targets.

Second, mechanically scanned UHFradars have inherently larger sidelobes thando higher frequency radars, which makesthem more susceptible to both intentionaljamming, and to inadvertent electromagnet-ic interference (EMI). EMI is particularlytroublesome at the lower, roughly 400 MHzfrequencies where the APS-145 operatesbecause there are so many powerful com-mercial occupants near this band.

The radar on the Advanced Hawkeye willdefeat these problems using two separate tech-niques. First, the APS-145 will be replaced bya digital, phased array radar called the ADS-18, whose 18 element array will allow elec-tronic scanning over 160 degrees, and whichwill mechanically rotate to provide 360degree coverage. The phased array antennaallows the radar to reduce its sidelobes elec-tronically, significantly reducing the jammingand EMI problem. It also provides more gainin the main lobe, giving better detectionranges. Second, the ADS-18 will also allowtemporal processing by providing three com-plete sets of measurements of the RF energyreturning from a single spot, which will allowit to distinguish the moving target within thefixed clutter background of that spot becausethe target will move slightly during the inter-val between each of the three pulses.

ADS-18 will provide a quantum leap inthe ability of the E-2 to detect ASCMs in thelittoral environment, as well as a raft of otherimportant targets.The next step is for the E-2 to provide its track information to shootersin the air and on surface ships in a way thatmaximizes their ability to shoot down the

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missile. This can be done in three ways,roughly corresponding to degrees of bothcapability and risk, and the CooperativeEngagement Capability (CEC) is central toall three.

The Centrality of CEC on E-2. CEC isa very sophisticated data link that allows dif-ferent platforms to share track informationon targets with a speed and accuracy thatallows one platform to shoot a weapon at atarget that another is tracking. In practice,CEC enables both very accurate cueing, toprovide warning to another platform that itis under attack by a target it cannot yet see,and to maximize that platform’s radar ener-gy management so that it can begin defend-ing itself as soon as possible. Moreambitiously, it allows for actual over thehorizon engagements, where one platformlaunches a weapon that another guides tothe target. In all cases, CEC extends the bat-tlespace available to combat the ASCMthreat, and this is particularly the case whenCEC is combined with Advanced Hawkeye.

At a minimum, CEC can give warning toany ship with terminal ASCM defenses thatit is going to come under attack from a veryspecific azimuth, allowing it to aim its shipself defense systems at that point on thehorizon and to prepare to deploy decoys.

For ships with Standard missile or SeaSparrow capability, CEC will provide cueingthat allows search radars to focus their ener-gy on the horizon, and will in some casesenable missile launch before the ASCM hasbroken the target ship’s radar horizon.

Most ambitiously, when combined withthe SM-2 Extended Range AntiaircraftMissile (ERAM), E-2/CEC will enable SM-2 intercepts out to 100 miles, even againstlow flying targets, at the very limits of the

kinematic range of the interceptor. ERAMsubstitutes an active seeker based on theAMRAAM (but with a larger aperture) forthe semi-active guidance of earlier SM-2s.This eliminates the need for an X-Band illu-minator within line-of-sight of the targetduring the end game of the engagement.Instead, using track data provided by E-2,ERAM will allow engagements where notonly is the intercept begun when the targetis beyond line-of-sight of the launcher, butcompleted as well.

Active Electronically Scanned Antennas(AESA) and Overland Cruise MissileDefense. Just as cruise missiles pose seri-ous threats to ships in the littoral, they alsopose threats to targets ashore. Overlandcruise missile defense presents all theproblems described above, with the addi-tional challenge that the endgame of theengagement is more challenging becausesmall aperture AAMs have more difficultylocating and homing on cruise missilesagainst a ground clutter background thanthey do at sea. One element in the solu-tion to this more challenging problem isthe AESA radars that will soon bedeployed on F-18E/F and, late in thedecade, on F-35. Compared to mechani-cally scanned radars, AESA radars havemuch more capability against low crosssection targets, both because they detectthem earlier, and because they track themmore accurately in azimuth and elevation.Earlier detection gives back battlespace,making for more favorable interceptgeometries, while better tracking accuracyenables a fighter to guide AAMs likeAMRAAM into smaller baskets withinwhich their terminal seekers are morelikely to acquire and home on the target.

Airborne electronic attack capabilities will grow, not decline in importance in the new security environment.

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Sensors, Weapons, andNetworks for Dealing With Mobile Targets

FROM THE FIRST USE of military avia-tion during World War I until DesertStorm, it was common for air-dropped

bombs to miss their targets by several thou-sand feet, and it therefore often took severalhundred or even thousand strike sorties todestroy a single fixed target with conven-tional weapons. Precision weapons havequickly changed that equation so that now itis reasonable to expect a single strike sortieto destroy several targets. Furthermore, theleap from “clear weather” to “all weather”precision attack was essentially completed inthe brief period between Desert Storm andIraqi Freedom. This revolution in precisionhas solved the fixed target problem in thesense that no opponent of the U.S. canexpect its fixed targets to survive long oncethey have been identified for attack. Ofcourse, nothing about this revolution assuresthat the opponent’s fixed targets will be dis-covered or correctly identified, not is itassured that effective attacks against fixed tar-gets will have decisive effects, but the simplefact that once identified a fixed target can bequickly destroyed does represent a revolutionin capability for U.S. air forces.

Both Enduring and Iraqi Freedom havealso demonstrated the “solution” to anothervexing problem for air forces; the ability forair forces to provide effective and timelysupport to ground forces engaged directlywith opposing ground forces. Such close airsupport operations have always been bedev-

iled by the following kill chain requirement.The targets in question were small andmobile and could only be reliably identifiedby friendly ground forces in close contactwith them; once targets were identified, itwas difficult for friendly ground forces tomark them for supporting forces; and oncetargets were marked, it was difficult for sup-porting air forces to bring a weapon to bearthat did not simultaneously threaten friend-ly and hostile forces. Fort McNair is onlyone of many monuments to the historic dif-ficulty of closing this kill chain.

The keys to completing the solution tothe close air support problem are three: thewide deployment among ground forces ofboth laser-based target markers/locators andground controllers; and the provision of datalinks (rather than just voice links) betweenground controllers and combat aircraft.Theobstacles to this achievement are no longertechnical, and the organizational/doctrinalobstacles that blocked progress in this mis-sion area in the past seem to have faded. It isin this sense that one can say that the closeair support problem is solved, and it is also inthis sense that one can say that the mobiletarget problem is not solved.

Solving the mobile target problem willrequire the development and tight integrationof new sensors, weapons, and networks forlinking them together.These will be used tofind, identify, track, locate, attack, and assessattacks against various types of mobile targets.The mobile targets of concern will includeopposing armored units and their commandposts, surface-to-surface and surface-to-airmissile launching units, and leadership targets.

The Revolution in Sea Strike

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Sensors,Weapons, and Networksin the Littoral Battlespace

The littoral battlespace for strike opera-tions against mobile/time critical targets willremain defined by the border between con-tested and uncontested air space, the maxi-mum altitude at which combat operationsoccur, and the maximum range into contest-ed air space that combat operations occur.Within that battlespace,naval strike forces willdeploy platforms carrying sensors andweapons, both manned and unmanned. Someof these platforms will be multi-purpose,while others will have a single purpose; somewill be autonomous, while others will beclosely controlled from other platforms; somewill need to send and receive large quantitiesof sensor data, while others will have lessstringent need for high bandwidth connectiv-ity; and finally, these platforms will vary in thedegree to which they can survive indepen-dently in the face of opposing defenses.

The capabilities of sensors, and the plat-forms they are deployed on, have the largestimpact on strike operations.The sensor plat-forms supporting future strike operations willprimarily use radar, signals intelligence orSIGINT (defined here as the passive collec-tion of either communications, or COMINT,or opposing radar emissions, or ELINT), andoptics exploiting either visible light orinfrared.They will generally be deployed oneither satellites or airborne platforms.

Space-based sensors look down at theirtargets from low (~200 miles), medium(~11,000 miles), or high (~22,000 miles)orbits. Satellites in high orbits remain in thesame position relative to the earth as itorbits, providing continuous coverage of thesame quarter to a third of the earth’s surface,meaning that three or four satellites can pro-vide continuous global coverage. By con-trast, satellites in low orbits move much faster

relative to the earth’s surface (90 minute ver-sus 24 hour orbits).They see much less of theearth’s surface at any one time, and it mighttake 12 hours for a single satellite to comewithin line-of-sight of the entire earth, butbecause they orbit so much closer to theearth, such satellites can deploy sensorswhose power-aperture or resolution productis insufficient for deployment in high orbits.

Historically, satellites have been valuablesensor platforms, particularly for intelligencepurposes, because they provide global cover-age, at least intermittently, and because spacewas not seriously contested as a deploymentmedium during the Cold War. By contrast,airborne platforms must operate in or along-side contested air space in order to comewithin line-of-sight of their targets. In caseswhere enemy defenses have not been sup-pressed, and where airborne sensor platformsare vulnerable to attack, they must patroloutside contested airspace and look hori-zontally across the battlefield.The maximumtheoretical detection range of almost anysensor under these circumstances is the dis-tance to the horizon, or the distance of atangent drawn between the platform and theearth’s surface. For air breathing platforms,the maximum altitude of operation is about60,000 feet, leading to a maximum detectionrange of about 250-300 miles.

This is significantly less field of view thaneven a satellite in low earth orbit, which cansee upwards of 500 miles outward alongeither side of its ground track. But an air-borne platform can orbit for many hours oreven several days within line-of-sight of thesame battlefield, whereas continuous cover-age of the same battlefield from low earthorbit requires a constellation of many tens ofsatellites in order to ensure one will alwaysbe within line-of-sight. Alternatively, air-borne platforms and satellites in high orbitsboth provide continuous coverage of the

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same battlefield, but airborne platforms pro-vide this coverage at distances that allow theuse of sensors whose power-aperture prod-uct is inadequate for deployment in highorbiting satellites.

In reality, maximum and realistic detec-tion ranges are almost always different. In thediscussion that follows, I will look at theactual limits on the performance of sensorplatforms, focusing on those deployed on air-borne platforms. When the discussion shiftsto how those sensors will be used in futuresea strike operations, I will bring space-basedsensor platforms back into the discussion.

As noted above, the maximum detectionrange of a sensor is determined by its dis-tance from the horizon. In practice, maxi-mum detection ranges often areconsiderably less because performancedepends on the diameter of the sensor’santenna or aperture, and the power availableto it – both of which consume weight andvolume, which are always scarce on airborneplatforms and extremely scarce on space-based platforms. Also, for a given wave-length, aperture size and design determinesthe angular resolution of the sensor, or theaccuracy of the bearing to the target it pro-vides. Again, for a given wavelength, passivesensors have longer range than active sen-sors, but on the other hand, active sensorscan provide range to the target, whereas pas-sive sensors provide only a bearing.

As a rule, SIGINT sensors are the onlyones whose detection ranges will alwaysextend out to the horizon, which on an air-borne platform will be 200 or more miles.For radars and optical sensors, detectionrange will depend more heavily on apertureand power, and therefore on volume andweight. For example, JSTARS’ radar has amaximum range of about 150 miles againsta ground target, while Global Hawk’s ismore like 100 miles, and a current fighter’s

radar might have a maximum range of 50miles. Passive optical sensors usually haveshorter ranges than radars, with even thewidest aperture airborne systems usually notexceeding 50 miles, and active optical sen-sors such as laser radars (LADARS) have theshortest ranges of all, with most airborneladars limited to approximately 5 miles.

Measured in terms of resolution or accu-racy, sensor performance is generally invert-ed, with very high frequency visible lightsensors and LADARS providing the mostaccurate bearings and ranges, and thesharpest images, followed closely by IR sen-sors, with the performance of radars andSIGINT systems lagging behind in thoseperformance metrics because of the muchlower frequencies of the signals they exploit.

Finally, sensors vary according to howthey are affected by weather, battlefieldobscurants like smoke, ambient light levels,foliage, and physical obstructions like terrainand buildings. SIGINT sensors and radars areleast affected by these factors, though the sig-nals they collect can be blocked by majorterrain obstructions, and radars do not pene-trate foliage well. By contrast, optical sensorsare dramatically affected by all or most ofthese factors. Neither IR or visible light sen-sors can see through cloud, and in addition,visible light systems are quickly blocked byobscurants such as smoke and become muchless effective in low light conditions.

Within their detection ranges, and giventhe limits on their resolution, different sen-sors perform different functions. SIGINTsensors detect radio or radar transmitters andprovide a line of bearing to them, with moresophisticated systems also providing ananalysis of the signal that allows identifica-tion of the class of the emitter, and in somecases, the specific emitter itself. Such systemscan also be used to develop an estimate ofthe location of the emitter by taking multi-

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ple lines of bearing from several look angles,but these estimates do not provide a preciselocation (<100s of meters) because of limitson the angular resolution of the bearings.

Radars detect objects with sufficientreflectivity (radar cross section) to provide adetectable return. When airborne radarslook down, terrain features provide a floodof returns that are difficult to distinguishfrom each other without specialized process-ing of the return signal. Today, in air-to-ground operations, the primary radar modesare synthetic aperture radar (SAR) and mov-ing target indicator (MTI).

SAR uses the movement of the radarplatform over time to create an artificiallywide “aperture” or antenna that can be usedto produce higher resolution images of afixed target than could be produced usingthe real aperture of the platform’s radarantenna.With SAR, a radar gains an imagingcapability with resolutions that approach butdo not equal those normally provided onlyat much higher optical wavelengths. By con-trast, MTI exploits the relative movement ofa moving target normal to the path of theradar platform. It does this by exploiting thefact that radar pulses reflected back from atarget moving toward the radar have a high-er, or doppler shifted, frequency than thepulses reflected from the stationary back-ground around the target.With doppler sig-nal processing, the radar can therefore beinstructed to “see” only moving targets, andthe background clutter can be filtered out.

When the two signal processing modesare combined, a SAR/MTI radar can detectand track moving vehicles over a wide areausing the MTI mode, or provide high reso-lution images of a series of spots within thatarea. SAR/MTI radars do not yet interleavethese two different modes rapidly enoughsuch that a target detected using the MTImode can be imaged using the SAR mode

as soon as it stops moving, and then imme-diately picked back up on MTI once it startsmoving again, but this capability will soonbe deployed and will improve the ability ofSAR/MTI radars to maintain continuoustracks of specific mobile targets.

Today, passive optical sensors are used pri-marily to collect very high resolution imagesor lower resolution video, and lasers are usedprimarily as range finders and target illumi-nators. In the not too distant future,LADARS will be deployed that will be ableto “measure” targets very precisely in threedimensions, albeit at relatively short range.

One other metric related to sensors con-cerns varying demands on processing capabil-ities and downlinks. SIGINT sensors used inpeacetime to collect and analyze signalsrequire large amounts of signal processing.That processing can either be deployed on alarge manned platform, such as an RC-135 oran EP-3, which is thereby able to perform itsprimary mission autonomously, or it can beseparated from the sensor platform by a datalink, allowing the use of smaller sensor plat-forms like U-2 or Global Hawk,which can flyhigher and longer, but which must downlinktheir output to a command center with therequisite processing capabilities. The requireddata links must be wideband, with data ratesmeasured in the multiple megabit/sec range,and can either be line-of-sight, to a commandpost within less than 200 miles or so, or viasatellite, in which case they could link any-where, albeit at lower data rates than the max-imum available using line-of-sight links.

One of the main purposes behind peace-time SIGINT collection and analysis is toform libraries of the characteristics of com-munication and radar transmitters of inter-est.These libraries, or portions of them, canbe loaded onto discs and carried on essen-tially any platform. During combat opera-tions, SIGINT surveillance assets use these

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libraries to generate immediate threat warn-ings of emitters within their field of viewthat require very little processing, and thatcan be broadcast on low bandwidth links.Today, large, sophisticated, intelligence plat-forms are generally used in this role, but notbecause of the need for their substantial pro-cessing or data link capabilities.

For example, assuming the provision of adigital threat library, a small UAV with a pas-sive receiver, very little onboard processingcapability, and a narrowband data link wouldbe able to provide real time threat warningsof hostile radars within its field of view.These warnings would include a classifica-tion of the emitter type, the exact time ofarrival and frequency of the intercepted sig-nal, and a rough bearing to the emitter’slocation. Future networks of such UAVsmight also provide immediate and preciselocation of threat emitters without signifi-cant additional processing or data linkrequirements, as I will discuss in more detailbelow.The point here is to note the dramat-ically different requirements for processingand data downlinks between tactical SIG-INT surveillance operations that exploitalready existing threat libraries, and thepeacetime SIGINT collection operationsthat generate and maintain those libraries.

The requirements for processing and datadownlinks for SAR/MTI radars are similarto those of peacetime SIGINT collectors.They can either be deployed on largemanned platforms, where most of the pro-cessing is done onboard by human opera-tors, such as on JSTARS, or on smallermanned or unmanned platforms such as U-2 and Global Hawk, which downlink theirdata continuously to ground-based process-ing centers.The processed radar output froma platform like JSTARS, consisting of SARimages and MTI tracks, can be transmittedusing narrowband links, whereas the down-

links from the U-2 or Global Hawk radarsare wideband, multi-megabit/second links.

Optical sensors generally do not require asmuch signal processing, but their require-ments for data transmission vary according tothe resolution desired,whether the imagery isstill or video, and whether it needs to betransmitted in real time. Real time transmis-sion of high resolution video requires enor-mous bandwidth, whereas still images andlow resolution video can be transmitted inreal time over narrowband links.

Quickly Detect, Identify, Track, Locate, and AssessAttacks on Mobile Targets

Successful attacks on mobile targets dependon networks of sensors that can quickly per-form the tasks described above. Each step inthis sequence creates different demands thatwill be reviewed below, but there are alsosome common challenges. First, mobile tar-gets will gain significant operational sanctu-ary if sensor networks do not function inmost weather conditions.This means eitherthat sensors must be chosen that can operatethrough clouds, or that sensors must bedeployed on platforms that operate beneaththe weather. Second, sensor networks musteither be designed to operate in the face ofopposing defenses, or those defenses must besuppressed or destroyed, thereby creatingsanctuaries from which sensor networks cansafely operate. This tradeoff applies equallyto the nodes of the network– the sensorplatforms themselves – and to the data linksthat connect them.

The Effects of Weather andDefenses

As a rule of thumb, the altitude band between15-20,000 feet is a good demarcation point

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regarding both weather and opposingdefenses. Above that altitude, sensor plat-forms will often be above significant cloudformations, but at the same time, they willalso be at heights that force the opponent touse longer range air defense systems that mustuse radar for initial weapon cueing and guid-ance. Below that altitude, clouds will be lesscommon, but at those lower altitudes, sensorplatforms will face shorter range air defensesthat can engage targets using only passiveoptical sensors, and are therefore essentiallyimmune to suppression or destruction.

Of course, against a capable opponentwhose longer range air defenses have notbeen suppressed or destroyed, there will beno operational sanctuary for airborne plat-forms above the battlefield. Under such cir-cumstances, if sensor networks have tooperate against unattrited defenses, sensorplatforms will need to operate from distanthorizontal standoff ranges or from space, orsensors will need to deploy on very stealthyplatforms that can not be detected or target-ed, or on platforms so cheap that redundantnumbers can be deployed in a self formingand self healing network that can sustainlosses and still function reliably.

Data links have different vulnerabilitiescompared to sensor platforms. Unlike radars,whose antennas are always designed to max-imize transmission and reception efficiencyin a specific direction, radio communicationsystems often use omnidirectional, or lowgain antennas. Such antennas are smallerthan high gain antennas and also eliminatethe need for accurate pointing. Both of thesecharacteristics make them useful for mobileplatforms where weight and volume are at apremium. Even though such antennas aremuch less efficient, sufficient power can begenerated except at the highest microwavefrequencies to establish reliable one waylinks out to the horizon.Thus the ubiquity

of military voice and data links at VHF andUHF using small, low gain antennas, partic-ularly on aircraft and ground vehicles. Therelatively large amount of power available atthese lower frequencies also explains whysatellite communications are possible atUHF with only slightly higher gain antennasthat need only be pointed at the sky to trans-mit or receive, and can still be deployed onalmost all platforms, albeit at much lowerdata rates than are available using line-of-sight links (50-100 kb/sec versus mb/sec).

The tradeoff that comes with dependingon these simple VHF and UHF circuits isthat they are inherently vulnerable to jam-ming by any transmitter within line-of-sightof the receiving antenna. VHF and UHFcommunication systems are not friendly tothe two main methods for dealing with jam-ming – high gain antennas and spread spec-trum or frequency agile waveforms – becauseboth of these antijam methods are bestimplemented using much higher, microwaveor millimeter wave frequencies.

High gain antennas with highly direction-al reception patterns “ignore” energy that isnot in their main beam, greatly reducing thearea from which an opposing jammer caninsert spurious energy into the antenna.Special waveforms that rapidly vary transmis-sion frequencies or use low power signalsburied seemingly randomly in the back-ground noise attack the jamming problemboth by making communication signalscovert and by making it difficult for the jam-mer to know what frequency to jam. Jamresistant communication systems depend onboth these techniques, and both require theuse of higher SHF or EHF frequenciesbecause high gain antennas at UHF would betoo large for mobile platforms, and becausesophisticated, jam resistant waveforms areprodigious consumers of bandwidth that isscarce at UHF. And finally, when bandwidth

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at the higher frequencies is used to buy jamresistance, data rates remain the same as ontoday’s links – kb/sec using satellite links andmb/sec using line-of-sight links.

The issue of data link hardness and relia-bility is central because upon this questionturns the design and viability of any conceptof operation that includes a battlefield sensornetwork. Absent jam resistant data links, itwill always be necessary to design in defaultmodes where the network is unavailable andindividual platforms must performautonomously. In addition, assuming jamresistant data links are pursued, their devel-opment will need to be tightly integratedwith the development of the sensor nodes inthe network because of the impact that jamresistance has on data rates, particularly forsatellite links. For example, the performanceof unmanned or lightly manned sensor plat-forms like Global Hawk and U-2 thatdepend on multi mb/sec or even gb/secsatellite links if there are no ground-basedcommand centers within line-of-sight willnot degrade gracefully if forced to fall backon narrowband data links, whereas mannedsensor platforms that do a lot of onboardprocessing of data could adapt much moreeasily to such an environment.

It is unlikely that jam resistant satellitecommunications will ever provide thesame data rates available using line-of-sightlinks. The receiving antenna in a line-of-sight downlink will normally be able toshield its sidelobes from jamming signals,whereas receive antennas on high orbitsatellites are much more exposed. Thismeans that jam resistant satellite links willalways depend on a high degree of spec-trum spreading that comes at the expenseof data rate. Today, when sensor platformsuse satellite links, they use commerciallinks designed to maximize data rates thathave no jam resistance.

A possible solution to this problem wouldbe a laser satellite communication system,using laser uplinks and downlinks. Lasers suf-fer from significant propagation losses in theatmosphere, but so much bandwidth is avail-able at optical wavelengths that it may stillprove possible to provide extremely high datarates. At the same time, because of theextremely high frequencies involved, thebeams produced are extremely narrow,whichmeans that even a receive antenna in highorbit might be able to null signals emanatingfrom outside a narrow cone surrounding thelegitimate transmitter. Absent the successfuldevelopment and deployment of such a sys-tem, satellite links will always present a harsh-er tradeoff between data rate and jamresistance than will line-of-sight links.

Assessing the potential physical vulnera-bility of space-based sensors and communi-cation satellites is a special case. Heretofore,satellites have enjoyed a virtual sanctuaryfrom attack. No war has ever been foughtbetween a country with satellites andanother with anti-satellites, never mind awar between two countries with both capa-bilities.Though both superpowers deployeddirect ascent anti-satellite systems duringthe Cold War, neither chose to use themagainst the other in peacetime, and theabsence of war between the superpowersleaves open the question of whether thesesystems would have been used in a war. Inany case, neither side’s anti-satellite systemswere very extensive, nor did they have thecapability to reach beyond low earth orbit.

Before attempting to judge the futurerelevance of this complicated issue, oneneeds to ask what role satellite-based sensorsor communications systems are likely toplay in the future in finding, identifying,tracking, locating, or assessing attacks againstmobile targets.

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Surveillance

Surveillance systems are characterized bylarge fields of view and persistence. Ideally, asurveillance system can continuously moni-tor the entire battlefield and pick out targetsof potential interest with a low false alarmrate. But even the best surveillance systemsgain this capability at the expense of theability to identify, track, precisely locate,and/or assess attacks against those potentialtargets.Thus, historically at least, surveillancesystems serve a cueing function for othersensors which complete the kill chain.

The surveillance challenge against anenemy’s forces in the field largely boils downto the problem of detecting vehicles.This isobviously a difficult problem, both becausemilitary vehicles are hard to distinguish fromother vehicles, and because all vehicles aredifficult if not impossible to detect from adistance if they are not moving, emitting asignal, or launching a weapon.

Moving vehicles can be detected by MTIradars in all weather at ranges that dependon the altitude and aperture of the sensor.Future airborne surveillance platforms mod-eled on today’s JSTARS, U-2, and GlobalHawk will be able to detect targets out to150 miles or more. On the other hand, facedwith reasonably advanced air defenses, suchplatforms need to standoff some 100 milesuntil those defenses are destroyed.

The desire to escape this tradeoff is onereason why a space-based radar program isbeing pursued. In principal, a constellationof such satellites could be deployed thatwould provide continuous coverage of theearth within its orbital planes. Deployed inlow orbit, such a constellation would needto include 20-40 satellites to ensure that oneis always above the horizon.The expense ofsuch a constellation has led to exploration ofthe alternative of deploying space-based

radars in medium orbits, where many fewersatellites would provide continuous cover-age, but where power/aperture productswould need to be much greater.A third andtechnically more challenging alternative hastherefore emerged envisioning a bistatic ormultistatic system in which a satellite inmedium orbit serves only as the transmitterin a network in which an airborne platformor platforms deployed within line-of-sight ofthe area of interest serve as the receiver.

The theoretical advantages of such anarchitecture are several. First, it would reducethe cost of achieving continuous coveragefrom the sanctuary of space without forcingthe satellite designer into a power/aperturerace that might not be winnable, particularlywhen using the MTI mode. Second, despitethis concept’s continuing dependence on air-borne platforms, it would not be as vulnera-ble to opposing defenses as a purely airbornesystem because the airborne platforms inquestion would be passive receivers only, andtherefore, in principal, highly stealthy andable to operate deep within rather thanalongside contested air space.Third, if imple-mented as a multistatic system with severalairborne platforms within line-of-sight of thesame area of interest, such a concept wouldalso enable the precise tracking of mobile tar-gets by exploiting trilateration, or the reduc-tion in angular resolution errors of singleplatforms by calculating the intersection ofthe error ellipses of two or three widely sep-arated platforms tracking the same target.

One of the challenges with space-basedradar is that it will be an expensive system,meaning that it will need to accommodatethe requirements of both the Intelligencecommunity and the Department of Defense,but these requirements will be difficult toreconcile. The Intelligence community’sprime interest is in a system that providesglobal coverage in peacetime but is less

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determined than DOD that that coverage becontinuous, whereas DOD is most interest-ed in continuity of coverage and might bewilling to sacrifice the loss of peacetimeaccess to deep inland areas that would resultfrom adoption of a multistatic system.

Vehicles can also be detected when theyuse a radio or a radar. SIGINT systemsdesigned to detect these signals have longerdetection ranges than radars because the sig-nals they collect are more powerful, not hav-ing suffered the attenuation of a two waytrip in which the power of the signal falls asthe fourth power of the distance traveled.Thus, for example, airborne SIGINT collec-tors such as RC-135, EP-3, and Guardrailcan see further into contested air space thancan airborne radars.

At the same time, the signals that SIGINTsensors collect are often highly directional.This applies with special force to ELINTsensors that collect radar signals. Since aradar’s main beam sends out a much morepowerful signal than do its sidelobes, andsince that main beam is usually aimed at thehorizon and scanned in both azimuth andelevation, the probability of detecting theradar’s signal can vary significantly dependingupon where the ELINT receiver is.

Thus, airborne ELINT sensors have amajor advantage over satellite-based ELINTsensors when used in a tactical setting. First,and most generally, an air defense radar’smain beam will rarely be aimed directly at asatellite because the air defense radar will beoriented horizontally to the horizon,whereas even a low orbit satellite will nor-mally be looking directly down.This meansthat space-based ELINT systems must becapable of detecting a radar’s sidelobes ifthey are to routinely and reliably detect it.Airborne ELINT systems have a doubleadvantage in that it is much easier for themto place their sensors in the path of a radar’s

main beam, and, because they are closer, it iseasier for them to detect a radar’s sidelobes.

Like radars, SIGINT sensors provide aline of bearing to their targets which haveerrors in angular resolution of one, several,or tens of degrees, depending on the quali-ty of the receiving antenna and the frequen-cy of the signal, but unlike radars, a SIGINTreceiver can not by itself provide a preciserange to the target because it is passive. Onthe other hand, because most emitting tar-gets are stationary while they emit, a SIG-INT platform can calculate an estimatedrange to the target over time by taking mul-tiple, separate bearings on the same signal.But in no case would the resulting positionestimate have an error ellipse with a radiusless than 100s of feet.

Finally, a vehicle can also expose itself todetection by launching a weapon, particu-larly a missile or a shell. Radars can some-times detect such weapons soon after theytake flight, and if they are flying anythingapproaching a ballistic trajectory, an estimateof their launch point can be quickly calcu-lated. When a vehicle launches a weaponwith a strong IR signature that lasts formore than a few seconds, it can often bedetected and tracked by missile warningsatellites in high orbits, both giving warningto those in the estimated impact area, andallowing a rough estimate of the launchpoint, and therefore of the launch vehicle’slocation if it has not moved. In principal, IRsensors could be deployed on airborne plat-forms and used for similar purposes.

In no case can an individual surveillancesensor complete the kill chain against avehicle using the same methods it used todetect it. None of the sensor modesdescribed above can precisely locate a vehi-cle; instead, they provide estimates of loca-tion with a radius of uncertainty measuredin 100s or 1000s of feet. An MTI radar on

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an airborne platform can provide a continu-ous track of a moving vehicle within its fieldof view, but a space-based system can onlydo so if its constellation is designed always tohave a satellite in view.Also, MTI radars cannot normally classify their targets, at leastbeyond such basic distinctions as between atracked or a wheeled vehicle. This maychange with the further development anddeployment of MTI radars that can imagemoving vehicles when those vehicles aregenerating rotational movement relative tothe radar, i.e. when rounding a turn on aroad, but the images generated will not behigh resolution. SIGINT sensors, on theother hand, will be able to classify their tar-gets immediately upon detecting thembecause of the wide deployment of already-developed specific emitter identificationcapabilities. Finally, none of the sensormodes described can reliably assess theresults of the attacks that result from theirinitial detections. Solutions to the rest of thekill chain will depend on some combinationof networking among surveillance sensorsand the introduction of imaging sensors.

Geolocation

Even during the latter part of the ColdWar, target location errors measured in thethousands of feet were acceptable becausean attacking aircraft only required knowl-edge of a target’s position relative to it, notthe target’s absolute position. Manned air-craft used their navigation systems to fly towithin line-of-sight of the estimated loca-tion of the target.As long as the accumulat-ed error in estimated target location and innavigation system performance was less thanthe field of view of the aircrew, they had agood chance of acquiring the target visuallyor with their radar. Once acquired in thisway, the target location error was irrelevant

because the accuracy of the attack dependedon how accurately the attacking aircraftcould calculate its position and rate of clo-sure relative to the target, not that target’sabsolute position.

This did not change with the early gen-eration of precision weapons. Weapons likePaveway 1, Walleye, or Maverick did notneed to know the absolute position of theirtargets. Rather, they went where they weretold to go by the pilot, who still found thetarget using methods basically similar tothose described above. It is the introductionof GPS-guided weapons that has driven theneed for precise geolocation of targets, witherrors measured in the 10s of feet ratherthan 100s or 1000s, and future weapons likesmall diameter bomb may create thedemand for even greater precision.

There are two fundamental approaches toprecise geolocation: one involves using net-works to compensate for the inaccuracies ofindividual sensors operating autonomously,while the other compares images of a targetcollected by a single platform to a database ofgeo-registered imagery (or precise terrain data).

Networks can be used to compensate forthe current inaccuracies of both SIGINTand MTI platforms. For example, in the caseof ELINT, if three ELINT antennas aredeployed within line-of-sight of a radar anddata-linked together, they can be used tomeasure the time of arrival of a single radarpulse at three widely separate locations.Withthree receivers, there are three separate pairsof receivers and the output of each pair canbe used to form a hyperbola of uncertaintyalong which the emitter lies. With threehyperbolae, there is only one point at whichall three intersect and that point can belocated with accuracy measured in 10s offeet. More ambitiously, if only two receiversare available, and at least one is moving rela-tive to the emitter, both the time of arrival

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and the precise frequency of the receivedsignal can be measured.The difference in thesignal’s time of arrival at the two platformscan be used to form one hyperbola of uncer-tainty, while the difference in the dopplershift of the signal at the two platforms can bederived to form a curved line intersectingwith the first hyperbola at only one point.

ELINT or COMINT networks usingtime difference of arrival or frequency dif-ference of arrival (TDOA/FDOA) signalprocessing do not require high data ratelinks, but they depend on very low latencies,and the performance of these networksvaries according to the geometry of the sen-sors relative to the emitter and the distanceof the sensors from the emitter. The idealgeometry has the sensors relatively close tothe emitter and essentially surrounding it.

One of the great strengths of these net-works is that they do not require sophisticat-ed, large aperture antennas.This means thatthere is great flexibility in designing thenodes of the network. For example, wheregroups of aircraft are already present on thebattlefield for other reasons, it will be possi-ble to turn them into a TDOA/FDOA net-work via Link 16 or its successor using theirRadar Warning Receivers (RWR) as thenetwork nodes. In addition, because theantennas can be so small, TDOA/FDOAnodes could be deployed on UAVs muchsmaller than those required to deploy radars.Thus, because the nodes are passive, andbecause they can be deployed on very smallplatforms, a small UAV-based ELINT net-work might prove to be the best means oftargeting the radars of advanced air defensesystems. Even more ambitious would be anELINT network whose nodes were covertlyplaced unattended ground sensors.

Networks can also be used to compensatefor MTI radar errors. If three widely sepa-rated radars are deployed within line-of-

sight of a moving target and data-linkedtogether, the error in target location causedby errors in azimuth resolution can be great-ly reduced by fusing the error ellipses gener-ated by each radar and finding theirintersection.This allows moving targets to betracked by MTI radars with an accuracyapproaching that needed to target a GPS-guided weapon. As with the SIGINT net-works described above, the area in which anetwork of MTI radars can precisely locatemoving targets is limited by the area inwhich the coverage of all three radars over-lap, and by the geometry of the radars rela-tive to the targets within that area.Thus, inboth cases, the performance of the networkdegrades if its nodes are forced to standofffrom contested air space. For example, whenstanding off in line abreast formation net-worked to precisely locate moving targets,three widely separated MTI radars able bythemselves to see 150 miles into contestedair space might collectively cover an arearoughly 50 miles deep, and their line abreastformation relative to the targets would alsoreduce the network’s location accuracy.

This point illustrates one significant dif-ference between SIGINT and MTI radarnetworks when used to locate ground tar-gets in contested air space. MTI radars putmuch greater demands on their platformsfor power and volume than do passive SIG-INT sensors, which means that it should bemuch easier to create SIGINT and especial-ly ELINT networks that use small, stealthy,and persistent platforms that can penetrateand operate within the coverage area ofunattrited, advanced air defenses.

The other general method of obtainingprecise target locations is to collect images ofthe potential target, compare them to animagery database which is already geo-regis-tered, and match the images collected to thedatabase. Databases now exist that provide

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precisely registered optical imagery and ter-rain elevation data to which can be comparedimages collected on the battlefield by camerasand SAR radars respectively.The term of artfor this process is called mensuration.

Today, mensurated optical and SARimages are produced on the ground after air-borne platforms like U-2 or Global Hawkor other national systems have downlinkedraw, very wide bandwidth data to groundstations where the data is processed, or theyare produced aboard larger, manned plat-forms like JSTARS and the Navy’s experi-mental “Hairy Buffalo” aircraft, which canmensurate SAR images on board. Eitherapproach today can require more than anhour to get targeting information from thesensor platform to the weapon platform.

Major efforts are already underway toreduce the time late associated with targetmensuration in order to speed up the processof striking mobile targets while they are atrest. One initiative is to give strike fightersand bombers an organic capability to mensu-rate images found by their own sensors.Another more ambitious goal is to create air-borne networks in which UAVs or UCAVscan downlink optical and SAR images byline-of-sight links to manned platforms capa-ble of doing the mensuration. The mannedaircraft could be command posts like the AirForce’s MC2A or the Army-Navy AerialCommon Sensor or individual strike fighterslike F-35. In either case, the objective will beto locate mobile targets precisely in real timeso that once found and identified they can bestruck before they move again.

Classification and DamageAssessment

Imaging sensors are one of several means ofobtaining precise target locations, but theyare often the only means of classifying or

identifying targets before attack, and ofassessing the results of an attack.Furthermore, depending on the rules ofengagement and on the future trends intechnology, it may be the case that many ormost targets will continue to require imagingsensors for both classification and damageassessment, as they almost always do today.

Certainly, there are instances on the bat-tlefield when classification and/or damageassessment can be gained by other means.For example, as was discussed above, SIG-INT sensors can classify emitters withoutneeding an image, though they can not per-form damage assessment beyond noting thatan emitter has gone off the air. Some kindsof mobile targets essentially classify them-selves by moving en masse in response tobattlefield events, such as an armored unitmoving to (or retreating from) an engage-ment.Thus, in the case of MTI radars, targetsor groups of targets can be sometimes classi-fied simply by the fact that they are wherethey are when they are doing what they are.The same caveats apply to damage assess-ment, where, for example, there will alwaysbe occasions in which a target’s destructionis easy to determine simply because of sec-ondary explosions that can be seen fromgreat distances.

But the fact remains that a significantnumber of mobile targets will likely remainwhich, by dint of their proximity to friend-ly troops or sensitive non-military facilities,their high value, or some other factor, willneed to be precisely identified using highresolution imagery before being attacked,and an assessment of those attacks will oftenneed to be performed using the same means.

Target classification and damage assess-ment are important for other reasons. Absenta process that leads to fairly rapid classifica-tion, surveillance sensors quickly becomeswamped because they detect many more

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potential targets than they can track. Inaddition, absent reliable classification, falsetargets are generated, wasting valuable track-ing time and causing the diversion ofweapons and weapon platforms. Also, whenreliable damage assessment is not available,multiple weapons must be assigned to highvalue targets to compensate for the possibil-ity that one might malfunction. And in theparticular case of attacks against opposingdefenses, a lack of reliable damage assess-ment prevents U.S. forces from exploitingsuccessful attacks. This is a particular prob-lem in the case of attacks against air defenseradars where, absent damage assessment, asuccessful attack is indistinguishable from asuccessful shut down by the opponent.

Beyond the common need for imagery,classification and damage assessment mayrequire different degrees of resolution.Whereas 1 meter resolution might be suffi-cient to distinguish military from commer-cial vehicles, and perhaps even certain typesof military vehicles from each other, 1 footresolution might be required to distinguishfriendly tanks from hostile tanks, or to dis-tinguish different variants of the same basicprime mover, such as the missile TEL, radar,and command post vehicles within a SAM-10 battery.

At the same time, determining damage toa target can require even higher resolutions,measured in inches, especially when vehiclesare attacked by penetrating weapons thatleave only a small hole, or by sub-munitionswhich sand blast the outside of the vehiclebut leave its basic structure intact. On theother hand, to avoid the need for such highresolutions, damage assessment can be per-formed probabilistically using much lowerresolution images. For example, followingthe model anticipated for AARGM/Quickbolt, any GPS/INS weapon with aterminal seeker could be programmed

immediately prior to detonation to relay itsposition, a health and status message, and animage of the target area via line-of-sightrelay back to its launch platform. In the caseof attacks against mobile targets, the purposeof the image would be to simply confirm ordeny the presence of the vehicle in the tar-get area, and its resolution could thereforebe quite modest.

Today, imagery of relatively high resolu-tion is routinely generated by optical,infrared, and SAR sensors, but the perfor-mance of these various sensors varies wide-ly according to their maximum range andresolution; their performance at night, inbad weather, and in the presence of battle-field obscurants; the weight, volume, andpower requirements they impose on theirplatforms; and their technical maturity.

Optical sensors have the best resolution,they can be given good detection rangeswhen provided modest aperture, and thetechnology of electro-optics is advancingrapidly, making the processing, storage, andtransmission of optical images easier by theday. But optical sensors are shut down com-pletely by weather and some important bat-tlefield obscurants, and are greatly degradedat night. IR imaging systems are approach-ing optical systems in their range and reso-lution, which has had a dramatic impact onstrike operations at night, but IIR systemsare also shut down by weather.Thus, as toolsof classification and damage assessment,EO/IR sensors must be deployable “underthe weather” if they are to be routinelyavailable. This reduces their field of view,increasing the number of platforms neededfor wide area coverage, and also exposesthose platforms to unsuppressed, short rangeair defenses.

These constraints already have led toefforts to improve the resolution of SARradars, which are “through the weather” sys-

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tems.Today, SAR imagery of 1 foot resolu-tion and slant range of more than 100 milesis generated by a variety of platforms, andimagery with 4 inch resolution has beendemonstrated, albeit from a slant range ofonly 25 miles. It is important to note thatthe resolution of SAR radar imagery isdetermined less by its angular resolution,which is not limited by its real aperture, as inother radar modes, but by its range resolu-tion. Range resolution, in turn, is limitedtoday by atmospheric distortion of individ-ual radar pulses, the degree of distortionvarying directly with slant range.Thus, withrespect to high resolution SAR imagery, andunlike MTI radar, standoff platforms can notuse aperture to compensate for distance,meaning that smaller penetrating platformswith smaller apertures will have an advan-tage in resolution.

Finally, work is being done to give MTIradars a better capability to identify movingtargets. One technique exploits the excellentrange resolution of these radars to form acrude image of the moving target, a tech-nique that is also being developed foradvanced air-to-air radars. A second tech-nique inverts the SAR radar’s normal routineby using the target’s motion to exploit thedoppler effect of an object rotating relative tothe radar, and to again provide an image of amoving target, a technique long used by theNavy to identify ships at sea. In neither caseare these techniques expected to producetruly high resolution images, but they willprove useful as a means of culling potentialtargets, reducing the number of tracks thatneed to be maintained before the target canbe further classified using other means.

Weapons

For obvious reasons, the appropriate weaponfor attacking a mobile target will depend on

the capability of the both the supportingsensor network, and on opposing defenses.For example, during World War II, air forcesgained a mobile target capability when theygained sufficient air superiority over theenemy’s fighters to fly patrols over the oppo-nent’s army in the field.When that army wasforced into large scale maneuver by friendlyground forces it filled up the local road net-work and aircraft flying very low and usingshort range cannon fire, bombs, and unguid-ed rockets could relatively easily find andattack such columns. Deployed in the num-bers and with the degree of air superiorityachieved by the Allies in the campaign toliberate France, tactical air forces wroughthavoc on the German Army at places likeMortain, where a German armored counter-attack was stopped from the air, and theArgentan-Falaise gap, where a GermanArmy was decimated as it sought to escapeencirclement by allied armies after they hadbroken out of Normandy.

The wide deployment by the early 1970sof vehicle-mounted, radar-guided, 20 and40mm AAA and hand held, heat seeking(infrared or IR), surface-to-air missiles(SAMs) greatly raised the cost of all low alti-tude attacks, whether against fixed or mobiletargets, and drove attacking aircraft to higheraltitudes. At these altitudes, smaller, mobiletargets were much more difficult to find andidentify, even when they were concentrated.Equally important, bombing accuracies fromhigh altitudes had not improved much sinceWorld War II, and were still often measuredin thousands of feet. At the same time, radar-guided SAMs were also eliminating the rela-tive sanctuary heretofore provided at thesehigher altitudes from ground-based airdefenses. An operational crisis resulted, expe-rienced by both the American and Israeli AirForces in their wars of this period, in whichbombing effectiveness against both fixed and

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mobile targets was low, and even high alti-tude operations faced serious oppositionfrom ground-based defenses. This crisis ledto major investments in technologies forsuppressing radar-guided SAMs, and forincreasing the precision of weapons droppedfrom medium to high altitudes.

Suppressing radar-guided SAMs wouldreestablish a high altitude sanctuary fromground-based defenses, while precisionweapons would greatly increase the lethalityand effectiveness of air operations from suchaltitudes. SAM suppression came to dependon specialized aircraft known as WildWeasels, equipped with sophisticated, pas-sive, direction-finding avionics which couldidentify and locate SAM radar emissions, andarmed with high speed, antiradiation missiles(HARMs) which, once fired at an activeradar, would either home on its emissionsand destroy it, or force it to shut down, caus-ing the SAM it was guiding to go ballisticand miss its target. The main method ofincreasing the lethality of bombing opera-tions was the development of the laser-guid-ed bomb (LGB). Aircraft equipped with alaser illuminator could drop bombs fromhigh altitude that would home on laserenergy reflected from the target.This great-ly increased the accuracy of bombingattacks, now measured in tens of feet, andalso made accuracy relatively insensitive toaltitude, allowing effective operation fromthe high altitude sanctuary established by thesuppression of opposing radar-guidedSAMs. But this development did not addressthe problem of finding mobile targets frommedium and high altitudes and was relevantmostly for attacks against fixed targets.

First generation LGBs were day/clearweather systems, and were used only in thelatter part of Vietnam after the Air Force andthe Navy experienced repeated failure inattacking high value fixed targets around

Hanoi. Post-Vietnam development of laser-guided weapons was dominated by the factthat Europe, like Vietnam during the mon-soon, usually had dense cloud cover, block-ing the use of LGBs from medium altitude,and that Soviet radar-guided air defenses –whether mobile or fixed – were so densethat there would be no sanctuary at mediumaltitude.This led to the development of for-ward looking infrared (FLIR) sensors thatwould allow low altitude operation at night,putting the laser illuminator under theweather and the aircraft under the radarhorizon, and also reducing to some degreethe exposure to optically-guided short rangeair defenses. But flying low and fast at night,a fighter with a LANTIRN pod and LGBswould still have had only modest capabilitiesto find its own mobile targets. This secondgeneration capability was not demonstratedon a large scale until Desert Storm, where itwas used from medium altitude against atotally suppressed air defense system againstboth fixed and mobile targets.

The wide deployment after Desert Stormof FLIR/laser illumination pods in both theAir Force and the Navy greatly increased thepercentage of the force with suchnight/clear weather precision strike capabil-ities against fixed targets and mobile targetswith a clear IR contrast relative to their sur-roundings. But even over the deserts of Iraqand Kuwait, the need for clear weatherproved troublesome, and it proved cripplingat times in the cloudy climate typical ofSerbia and Kosovo, a characteristic obtainingthroughout the temperate zones of theworld, including the entire Asian littoral.

The solution to this problem wasweapons that integrate GPS and inertialnavigation systems (INS). IntegratedGPS/INS provides a through the cloud,weapon guidance capability that is compact,relatively cheap, and which can be made

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robust against countermeasures. On theother hand, unlike LGBs, platforms carryingGPS-guided weapons are still generallyunable to geolocate targets with their ownsensors with the precision needed for anorganic, closed loop targeting system. GPSweapons have played a large role in bothEnduring and Iraqi Freedom, but when usedagainst mobile targets the coordinates fortheir targets were provided by other plat-forms, often an individual on the groundwithin line-of-sight to the target.

Weapons vary according to the range andspeed of their delivery. Standoff range is use-ful when opposing defenses are not sup-pressed, and speed of flight will determinethe time lag between weapon launch andimpact. GPS or laser-guided gravity bombshave ranges of at most 10-15 miles, wellwithin the range of most radar-guided airdefense systems. Glide bombs like JSOW canboost weapon range to about 40 miles,which may be far enough to protect stealthaircraft from a SAM-10, but in that case theymust be carried internally.This is not a prob-lem for B-2, but internal carriage becomes areal constraint with aircraft like the F-22,whose weapon bays are small. Hence thesmall diameter bomb program, which is aGPS-guided glide bomb with a maximumrange of 40 miles, a 250 lb. payload, and ter-minal seeker.At 40 miles range, the time-to-target for a glide bomb is at least 8 minutes.

Current rocket-propelled standoff wea-pons like AGM-130 and 142 can deliver500-1000 lb. payloads with less time-to-targetover the same distance as a glide bomb, butthese weapons are too large for internal car-riage by any stealth aircraft, while at the sametime they do not provide enough standoff fornon-stealthy aircraft to use them against tar-gets defended by double digit SAMs.

The HARM antiradiation missile is aspecial case in this category. It is faster than

the other missiles, but carries a very smallwarhead. But like other air-launched rock-ets, it too is currently too large to fit inter-nally on stealth fighters, and lacks the rangeto be used by non-stealthy aircraft againstdouble digit SAMs. One element of theAARGM program is to develop a newmotor for HARM which would increaseboth speed and range, while at the same timeallowing internal carriage.

Air-launched jet-propelled cruise missileslike JASSM and SLAM are small enough tobe carried externally by non-stealthy fightersand can reach out to about 150-200 milescarrying 500 lb.warheads.But at those ranges,which are necessary if the launch platformsare not stealthy, flying subsonically at less than10 miles a minute, the weapon takes at least15-20 minutes to reach the target.

Cruise or ballistic missiles can also belaunched from over the horizon by surfaceships or submarines, or from friendly territo-ry. Standard 21” diameter and 20’ longlaunchers can carry ballistic missiles thatcome in variants with ranges from 100-300miles and payloads varying from 1000 to 400lbs., or cruise missiles that can carry a 1000 lb.payload to a maximum range of 1000 miles.

Weapons also vary in other respects.Gravity bombs like Paveway and JDAM costas little as $20,000 apiece, whereas the otherweapons described above range in unit costfrom $300,000 for the baseline JSOWupward. In principal, any air-launched grav-ity, glide, or rocket- propelled weapon couldbe targeted by its launch platform, whereasbeyond about 40 mile range, offboard target-ing usually becomes necessary. For targetingfixed targets or mobile targets at rest,weapons require either a laser spot to homeon, a precise GPS coordinate, an image ofthe target and a terminal seeker with scenematching capability, or a terminal seeker anda data link back to the launcher that allows

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the launcher’s aircrew to do the scenematching.Traditionally, weapons designed toattack moving targets have used an opticalseeker with a tracker and have relied on thepilot to designate the target and lock on theseeker before launch.

Future weapon developments willinclude new kinds of terminal seekers,smarter sub-munitions, and better scenematching or target recognition algorithms.Today’s terminal seekers rely on scenematching and are usually passive, but futureterminal seekers may use active millimeterwave or laser seekers more capable of recog-nizing targets themselves, potentially elimi-nating the need for a prior image of thetarget. Active seekers, if made small enough,can be used in smart sub-munitions which,if used against dense target arrays, could pro-duce multiple kills from a single weapon, andcould also significantly reduce the demandson targeting networks, particularly in regardto target geolocation accuracy.

At the same time, scene matchingweapons could also be improved.Today, theterminal seekers on scene matching weaponsusually collect IR or visible light images andcompare them to templates generated usingthe same phenomenology. So an IR seekerneeds an IR image as a template, or an opti-cal seeker needs an EO image. In principal,

the launch platform could generate thesetemplates but only in clear weather or underthe weather. Future scene matching weaponsmay retain their relatively simple, passive,EO/IR seekers, but use scene matchingalgorithms that allow target templates to bedeveloped by either visible, IR, or SARimages. For example, this would allow astrike fighter to use its SAR to target a cheapgravity or glide weapon through the weath-er and in real time.

In addition to reducing the need for net-works to produce precise target locationinformation, smarter sub-munitions and bet-ter scene matchers would also reduce thecurrent dependence on GPS for weaponguidance and possibly give weapons an equalcapability against stationary or moving tar-gets. In both cases, INS systems would putthe weapon inside its terminal seeker’s basket,with smart sub-munitions probably costingmore, but also providing a much larger bas-ket, whereas smarter scene matchers wouldlikely remain very cheap but also dependenton their launch platform for a more accurateinitial target location. Smart sub-munitionswould be most compatible with standoffweapons for use in higher threat environ-ments, while smart scene matchers would bemost relevant when strike fighters havegained a medium altitude sanctuary.

Future strike fighter sensors will be both integrated and networked with other platforms.

When ready for operational use, carrier-based UCAVS will provide unprecedented range and endurance to carrier strike

groups which value those attributes highly.

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Conclusions

IN CONCLUSION,one way to assess the futureof naval aviation is to look at its progressionto this point. For example, consider the fol-

lowing words, written sometime in May orJune 1944 by Bernard Brodie, known thenprimarily for his work as a naval historian.

“The peculiar value of the airplane inmodern naval war extends over twovery diverse fields – reconnaissanceand attack. Almost every aerial bombthat strikes home makes the frontpage of the news, but the accomplish-ments of the aerial observer are gen-erally and understandably passed overin silence. Yet it may be doubtedwhether the reconnaissance value ofaircraft over the seas adds up to muchless than their attack value. The twocannot as a rule be separated, butgreat decisions have been made andlarge operations put in progress onthe basis of intelligence gained fromthe air. Correct intelligence is theleast publicized but also the most ele-mental prerequisite of successful war-fare.”xvii

One can see in these words the genesis oftoday’s carrier-based strike fighters and land-based maritime patrol aircraft (as well as thelong history of greater public attention to theformer over the latter). One can also see bycomparison to today one of the main changesin the structure of naval aviation thatoccurred in the intervening years – the emer-gence of the multi-mission helicopter.Helicopters combined the reconnaissance and

strike function in a single platform that can bedeployed on the smallest of naval combatants,making the surface community air capable,and allowing the widest possible dispersion ofaircraft within the fleet.

Much about today’s aircraft has obviouslychanged, and much will change in the future,but they will likely remain focused on recon-naissance and strike broadly defined, both atsea and ashore, where they will retain uniqueadvantages in the altitude, speed, and maneu-verability of their movements compared toplatforms which are limited to maneuveringin two dimensions.

Some of the changes to expect in thefuture have already begun, as in the develop-ment and deployment of unmanned aircraftto complement and perhaps eventuallyreplace manned aircraft. For the near to mid-term, it appears that this trend will be mostpronounced in those applications whererange, endurance and in some cases, altitudeare the most valued attributes. By compari-son, manned aircraft will likely remain abovethe battlefield for the foreseeable future inthose applications where disparate, oftenambiguous, sensor inputs must be quicklyfuzed, assessed, and acted upon quickly anddecisively in order to achieve the desired tac-tical outcome.

The most important and perhaps misun-derstood change which is unfolding lies, onthe one hand, in the increasing benefits thatwill flow from networking the sensors frommultiple aircraft toward a common purpose,and on the other in the concomitant poten-tial that the network itself will become a newsource of vulnerability, either through the

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insecurity of its links, or the indispensabilityof one of its nodes. The potential benefits tobe derived from networking are overwhelm-ing, as are those associated with unmannedplatforms, but much discussion to this pointis characterized by less focus on the poten-tial vulnerabilities and constraints.

For example, many advocates of “net-centric warfare” possess a near mystical beliefin both the power and future availability ofbandwidth at radio frequencies on and overfuture battlefields. Certainly, much band-width there already is, and more there willbe, but all RF bandwidth used for commu-nication or data relay purposes can be opti-mized either to maximize data rates orminimize vulnerabilities to detection andjamming but not both. Today, many of thebest examples of net-centricity that havebeen demonstrated depend on links withvery high data rates. Networks dependenton such links would not be viable on manyfuture battlefields, requiring that their nodesretain some capability for autonomous oper-ation. But network designers anxious toreap the maximum benefits from a net-worked force, and infused with the assump-tion of infinite bandwidth, will be temptedto design network nodes that can not func-tion autonomously.

These issues speak both to the question ofwhether to man airborne platforms or not,and whether to deploy multi-sensor plat-forms on which some degree of sensorfusion occurs onboard or to deploy highlyspecialized single sensor platforms whoseoutput can only be fuzed with other sensorsusing a network. In the case of reconnais-sance and surveillance aircraft, the trendstoward unmanned operation and networkdependence can and should be more pro-nounced than with strike aircraft, whereboth the operating environment and thenature of the mission will often require that

sensors, weapons, and decision makers becollocated on the same platforms.

Another set of conclusions concerns like-ly future sensor capabilities in different envi-ronments. Four distinct environments areimportant: air (and space), sea surface, land,and undersea. Variations in terrain (orhydrography) will have significant effects insome environments (land and undersea) byreducing detection ranges. Variations inweather will be important wherever optical(as opposed to radar) sensors play an impor-tant role on the battlefield. Clutter, when itexists, will greatly complicate the ability ofsensors to identify moving targets ashore andfixed targets undersea.

For these and other reasons, conclusionsabout future sensor capabilities for useagainst airborne and space-based platforms,or against fixed land targets should vary con-siderably from the capabilities for use againstmobile land targets or stationary or slowmoving undersea targets. In the formercases, detection ranges are relatively long andclassification is often straightforward, where-as in the latter cases, detection ranges arealmost always much shorter and classificationmuch more difficult. In the former cases,radar is dominant, whereas in the latter casesa high degree of multi-spectral sensor fusionis often necessary.

As important as these largely technicaltrends will be a series of political and doctri-nal trends. The most important politicaltrend is the reduction in reliable and pre-dictable access to overseas bases that accom-panies the reduction in salience of formalalliances as compared to more informalcoalitions. This trend is based on a basicstructural change in the external securityenvironment and is therefore likely to last forthe foreseeable future. It is the main reasonwhy sea basing has grown in such relativeimportance in both major combat opera-

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tions such as Enduring Freedom and IraqiFreedom, and in operations against globalterror networks which often incubate andmetastasize in exactly those regions of theworld where one wouldn’t want access tobases ashore even if it was available.

At the doctrinal level, the most importanttrends for naval aviation are the evolutiontoward distributed air-ground operationsashore, and toward the need for a dominantdefense of the sea base in a littoral asopposed to a blue water environment. Theformer creates the demand for a persistentand distributed air force capable both of pre-venting major concentrations and move-ments of enemy forces on the ground,enabling the use of smaller and lighterfriendly ground units, and of rapidly andprecisely supporting friendly forces whenthey encounter and engage smaller pocketsof enemy resistance that cannot be detectedand attacked from afar.

The need for a dominant defense of thesea base in the cluttered littoral environmentsplits into two primary challenges: the chal-lenge of recovering detection, classification,and engagement ranges against cruise missilesand their launchers operating ashore, on thesea surface, and in some cases undersea; andthe challenge of adapting to the inherentlyreduced detection, classification, and engage-ment ranges against submarines (and mines).

As this report shows, naval aviation is pro-gressing toward solutions to each of thesechallenges. Success in these areas will in turnenable the full exploitation of the sea base’scapabilities to influence and control eventsboth on the high seas and ashore, against thefull spectrum of threats. It is necessary tosustain this progress in the coming years anddecades because the future security environ-ment will brook no alternative solutions tothe major security challenges faced by theUnited States.

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i Conduct of the Persian Gulf War (Washington, D.C.: U.S. Department of Defense,April 1992), p. 35.

ii Peter Grier,“Pentagon Speeds Forces to Hot Spots,” Christian Science Monitor, October 18, 1994,p. 1.

iii Douglas Jehl,“Saudis Admit Restricting U.S.Warplanes in Iraq,” New York Times, March 22, 1999,p. 6.

iv The U.S. Commission on National Security, New World Coming (Washington, D.C.August 1999) p. 7 <http://www.nssg.gov/Reports/>.

v Report of the National Defense Panel, December 1997, pp. 12–13 <www.dtic.mil/ndp/>.

vi On the United States being an offshore balancer of last resort, see Christopher Layne,“From Preponderance to Offshore Balancing:America’s Future Grand Strategy,” International Security,Vol.22, No. 1 (Summer 1997), pp. 112–123. I am predicting that the United States will adopt that broad role for reasons quite different from those proposed by Layne, but his description of how such strategy might work in practice is useful. On Britain’s historic role as an off shore balancer in Europe, see Daniel A. Baugh,“British Strategy during the First World War in the Context of Four Centuries: Blue-Water versus Continental Commitment,” in Daniel Masterson, ed., Naval History:The Sixth Symposium of the U.S. Naval Academy (Wilmington, Del.: Scholarly Resources Inc.,1987), pp. 85–110.

vii At about 500-600 km range, missile designers must start considering staging if they wish to preserve a reasonable payload.Though a two stage TBM is far from infeasible, it is a leap ahead in both technology and cost, and given the simplicity of the cruise missile alternative, the latter may be preferred.

viii For an excellent discussion of such TBMs and cruise missiles, from which this discussion of thevulnerability of fixed targets draws liberally, see John Stillion and David T. Orletsky,AirbaseVulnerability to Conventional Cruise-Missile and Ballistic-Missile Attacks:Technology, Scenarios,and U.S.Air Force Responses (Santa Monica, CA.: Project Air Force, RAND, 1999).

ix Again, in the long run, the U.S. Navy’s recent decision to give its next surface combatant electric drive may prove fortuitous if this provides the power supply for terminal, directed energy defenses using solid state or free electron lasers if and when the latter become feasible.A surface ship is the perfect candidate for such a terminal defense because it is continuously moving, which means it can only be attacked by weapons with terminal seekers that a laser can burn.At the same time, it is among the largest and highest value moving targets, which means that unlike ground vehicles it hasa large, organic supply of power which, on an electric drive ship, can be rapidly turned into electricity to power a laser.

x These are all points made by Stillion and Orletsky,Airbase Vulnerability, p. 31.

xi Edward N. Luttwak, ‘The Operational Level of War,” in Strategy and History: Collected Essays,Vol. 2 (Transaction Books, New Brunswick, N.J.: 1985) pp. 182-186.

xii For a summary of this debate, see Harvey M. Sapolsky and Jeremy Shapiro,“Casualties,Technology,and America’s Future Wars,” Parameters,Vol. XXVI, No. 2 (Summer 1996) pp.119-127.

xiii The best account of those events is Mark Bowden’s masterful Black Hawk Down:A Story of Modern War (New York:Atlantic Monthly Press, 1999).

xiv Stephen Walt,“Muscle-bound:The Limits of U.S. Power,” Bulletin of Atomic Scientists, March April 1999, p.44.

xv Douglas Barrie,“India Begins To Receive Russian Missiles for Subs,” Defense News, October 23,2000, p. 60.

xvi For a vivid description of these early LGB operations, see Jeffrey Ethell and Alfred Price, One Day In A Long War (New York: Random House, 1989).

xvii Bernard Brodie, A Guide to Naval Strategy, Third Edition (Princeton, N.J.: Princeton University Press, 1944) pp. 211-212.

Notes

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