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ACKGROUND PAPER

ounterforce Issues for theU.S. Strategic Nuclear Forces

nuary 1978

Congress of the United StatesCongressional Budget Office

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COUNTERFORCE ISSUES FOR THEU.S. STRATEGIC NUCLEAR FORCES

The Congress of the United StatesCongressional Budget Office

For sale by the Superintendent of Documents U.S. Government Printing OfBceWashington, D.C. 2M02

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PREFACE

In recent years, concern has grown that one element ofthe TRIAD of U.S. strategic nuclear forces, land-based ICBMs,

might become vulnerable to a first strike by an improving SovietICBM force. The fiscal year 1979 budget will present to theCongress several programs that respond to this growing threat.This background paper, prepared at the request of the SenateBudget Committee, discusses the significance of the Soviet coun-terforce threat against Minuteman and the arguments for andagainst the development of a similar U.S. capability. Togetherwith the forthcoming companion paper on retaliatory issues,it supports a forthcoming Budget Issue Paper for fiscal year 1979on strategic nuclear forces.

This paper was prepared by Robert R. Soule of the NationalSecurity and International Affairs Division of the CongressionalBudget Office, under the supervision of John E. Koehler. Theauthor wishes to acknowledge the assistance of Virginia G. France,David R. Martin, John Shewmaker, Carl R. Neu, Linda S. Moll, NancyJ. Swope, and Patricia J. Minton. Cost estimates were provided byEdward Swoboda of the Budget Analysis Division of the Congres-sional Budget Office. Editorial assistance wa s provided b yPatricia Johnston. In accordance with CBO's mandate to provideobjective analysis, this paper offers no recommendations.

Alice M. RivlinDirector

January 1978

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CONTENTS

PREFACE iii

SUMMARY xi

CHAPTER I. INTRODUCTION 1

CHAPTER II. COUNTERFORCE STRATEGIES 5

CHAPTER III. U.S. STRATEGIC VULNERABILITY 9

U.S. ICBM Vulnerability 9U.S. Bomber Vulnerability 22The Submarine-Based Force 24The Vulnerability of the TRIAD 27

CHAPTER IV. U.S. COUNTERFORCE CAPABILITY 31

Deterrence and Strategic Stability 31Silo-Based Counterforce Capability 35Mobile-Based Counterforce Capability 38

CHAPTER V. U.S. OPTIONS 45

Finite Deterrence 45Slow Counterforce 46Prompt Counterforce ... 50

APPENDIX A. THE SNAPPER FORCE EXCHANGE MODEL 57

APPENDIX B. U.S. ICBM VULNERABILITY IN THE MID-1980S 59

APPENDIX C. U.S. ICBM VULNERABILITY IN THEMID-TO-LATE 1980s 67

APPENDIX D. GLOSSARY 75

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TABLES

TABLE 1. ESTIMATED SOVIET STRATEGIC NUCLEAR FORCES, 1985 . 16

TABLE 2. ESTIMATED U.S. STRATEGIC NUCLEAR FORCES 18

TABLE 3. U.S. STRATEGIC FORCES SURVIVING A FIRST STRIKE . 30

TABLE 4. SOVIET ICBMs SURVIVING A U.S. FIRST STRIKE 34

TABLE 5. TOTAL SURVIVING SOVIET AND U.S. ICBMs AFTERSOVIET FIRST STRIKE AND U.S. SECOND STRIKE 37

TABLE 6. COSTS OF FORCES FOR FINITE DETERRENCE 47

TABLE 7. COSTS OF FORCES FOR SLOW COUNTERFORCE 49

TABLE 8. COSTS OF FORCES FOR PROMPT COUNTERFORCE 52

TABLE 9. SUMMARY OF COSTS OF THREE OPTIONS 54

APPENDIX TABLES

TABLE B-l. ATTACK 1: ONE GRDUNDBURST 60

TABLE B-2. ATTACK 2: ONE AIRBURST, ONE GROUNDBURST 62

TABLE B-3. ATTACK 3: ONE AIRBURST, ONE GROUNDBURSTAND REPROGRAMMING FOR RELIABILITY 64

TABLE C-l. ATTACK 1: ONE GROUNDBURST 68

TABLE C-2. ATTACK 2: ONE AIRBURST, ONE GROUNDBURST 70

TABLE C-3. ATTACK 3: ONE AIRBURST, ONE GROUNDBURSTAND REPROGRAMMING FOR RELIABILITY 72

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SUMMARY

U.S. strategic nuclear forces consist of three parts: land-based intercontinental ballistic missiles (ICBMs), long-range

bombers, and submarine-launched ballistic missiles (SLBMs).Together these three parts are known as the TRIAD.

These forces are an important part of perceived U.S. militarypower, and as such serve a variety of political and militaryfunctions; chief among these functions is that of deterring aSoviet nuclear attack. To deter such an attack, U.S. forces mustbe capable of surviv ing a Soviet nuclear attack against them(usually referred to as a counterforce attack) in sufficientnumbers to threaten retaliation that would be unacceptable to theSoviet Union.

In recent years, concern has grown that one element of theU.S. TRIAD, land-based ICBMs, might become vulnerable to a firststrike by a Soviet ICBM force consisting of increasingly accuratemissiles armed with Multiple Independently Targetable ReentryVehicles (MIRVs). Although current and programmed U.S. forceswill continue to provide a capability to destroy Soviet urbanindustrial centers in a second strike, additional nuclear weaponsmight be required for deterrence of a Soviet counterforce strike,since a U.S. threat to destroy Soviet cities might not be credibleas long as U.S. cities remained intact and the Soviet Unionretained forces capable of destroying them. Some analystsargue that unless U.S. strategic forces were capable of retali-ating against the Soviet ICBMs remaining after a first strike

against the United States, the Soviet Union might be able to gainan advantage by destroying the U.S. land-based missile force.

The need for several programs to modernize and augment U.S.strategic forces will depend upon judgments made about the desir-ability of developing a second-strike counterforce capability.These judgments will affect decisions about such weapon programsas the following:

o Development and procurement of the MX missile, a morepowerful, more accurate, and potentially mobile ICBM;

o Development and procurement of the Trident II missile, amore powerful, more accurate submarine-launched missile;

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o The ultimate size of the Trident submarine fleet and thepace of submarine construction; and

o The number of bomber-launched cruise missiles and cruisemissile carriers.

U . S . S t r a t e g i c Vu l n e r a b i l i t y

A successful counterforce attack on land-based ICBMs inhardened underground silos would require a force of MIRVed mis-siles with high accuracy and warhead yield. Many observers haveexpressed concern that the large-scale deployment of the newgeneration of MIRVed Soviet ICBMs (the four-warhead SS-17, theeight-warhead SS-18, and the six-warhead SS-19) may pose a sig-nificant threat to the U.S. ICBM force. This modernizationprogram will apparently not be significantly constrained by aSALT II agreement.

The 6,000 to 7,000 independently targetable warheads that mayeventually be in the Soviet ICBM arsenal would not, however, allbe useful in a simultaneous attack on U.S. land-based missiles.An important attack constraint results from the effects of nucleardetonations on warheads entering an area where previous explosionshave taken place, a phenomenon known as fratricide. This phe-nomenon would probably limit an attacker to one or two explosionsper target. As a result, the current generation of Soviet MIFVedICBMs, if their accuracy proves to be no better than 1,500 to1,200 feet, could probably destroy no more than about 40 to 60

percent of the U.S. land-based missile force. Fur the rm ore ,even damage of this magnitude would be a risky prospect for anattacker, since a great deal of uncertainty surrounds estimatesof missile reliability and accuracy, warhead yield, and siloresistance to nuclear effects. These uncertainties together raisethe possibility that a Soviet counterforce attack would leave manymore U.S. missiles surviving than anticipated.

If the Soviets are to enhance their counterforce capability,they must improve the accuracy of their missiles. Reports haveindicated that the Soviets have yet another generation of ICBMsunder development, presumably being designed for improved accur-acy. Preventing the development and deployment of more accurate,multiple-warhead Soviet ICBMs will be an important task for futurearms limitation negotiations. If new missiles capable of accura-cies of about 600 feet were developed and deployed, then by themid-to-late 1980s, over 90 percent of the U.S. ICBM force might bevulnerable to a Soviet attack that allocated two warheads to eachsilo. A Soviet leadership could not, however, count on damageof this magnitude, since there would be a 5 percent chance that

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only 75 percent would be destroyed, leaving 250 U.S. ICBMs re-maining after a counterforce attack rather than 100.

In any case, ICBMs are only one part of the U.S. nucleararsenal. In fact, about half of the equivalent megatonnage in theU.S. force, a measure of area destructive power, is carried bylong-range bombers, while half of the warheads, a measure of theability to attack large numbers of targets, are carried by submar-ine-launched ballistic missiles. Since alert bombers and submar-ines at sea will probably maintain their survivability and theirability to penetrate enemy air defenses into the foreseeablefuture, even a successful Soviet attack on U.S. ICBMs would notcompromise the ability of the United States to inflict devastatingretaliation on the Soviet Union.

U.S. Counterforce Capability

The threat to retaliate against Soviet cities might not detera Soviet counterforce attack, since the United States would be

reluctant to attack Soviet cities as long as U.S. cities remainedintact and the Soviet Union maintained reserve forces capable ofdestroying them. For this reason, the United States might desirean ability to carry out a counterattack against Soviet ICBMs todeter a Soviet counterforce strike. If U.S. forces that surviveda Soviet first strike were capable of destroying most of theSoviet ICBMs held in reserve, then no possible gain would resultfrom a Soviet attack, and deterrence might be enhanced.

There are several objections to any U.S. attempt to buyforces designed to fight counterforce wars. First, even with thecomplete loss of the ICBM force, the United States would stillhave enough weapons for counterattacks on Soviet conventional

military targets or isolated economic assets, in addition to thoseneeded for attacks on Soviet cities.

Most importantly, a U.S. second-strike counterforce capa-bility mi ght be indistinguishable to the Soviet Union from afirst-strike force. Because of their relatively greater depen-dence on ICBMs, the Soviets might be particularly sensitiveto a U.S. counterforce threat. As a result, a Soviet leadershipfacing a serious international crisis might feel strong incentivesto launch a preemptive strike against U.S. strategic forces beforetheir own land-based missiles could be destroyed.

A threat to the Soviet ICBM force might compel the SovietUnion to build new weapons to compensate for the vulnerability oftheir silo-based missiles. Thus, a new round of U.S. arms produc-

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tion might reduce, rather than enhance, U.S. security. Proponentsof a U.S. counterforce capability suggest that the Soviet armsbuildup is already threatening strategic stability and that a

threat to the survivability of Soviet ICBMs would force the SovietUnion either to negotiate an agreement limiting the counterforcethreat or to reduce their reliance on silo-based missiles andshift to a more survivable basing system. In either case, thesurvivability of land-based missiles would be enhanced and incen-tives to strike first would be reduced.

If a second-strike counterforce capability were desired, theUnited States would require additional and more sophisticatedweapons. Silo-based weapons, such as the existing Minutemanforce, are becoming increasingly vulnerable to attack, and, in anycase, could not destroy more than about 40 to 60 percent of theSoviet ICBM force even in a first strike. Even a U.S. weapon asformidable as the MX missile, if based in vulnerable Minutemansilos, would lose its ability to counterattack effectively againstSoviet reserve ICBMs as the Soviets improve the accuracy andcounterforce capability of their own forces. Moreover, silo-baseddeployment of a weapon as theatening as the MX missile woulddestabilize the nuclear balance, since in a crisis the Sovietsmight have a strong incentive to try to knock out a U.S. forcethat could destroy over 90 percent of Soviet ICBMs if the UnitedStates were allowed to shoot first.

Mobile weapons would be able to survive a Soviet first strikeagainst them and could therefore be effective in a second strike.Mobile counterforce weapons include MX missiles that could move atrandom in ten- to twelve-mile long underground trenches or amongseveral protective above-ground shelters, Trident II submarine-launched missiles, and bomber-launched cruise missiles. Theseweapons have different implications for strategic stability thando silo-based forces. Since Soviet forces could probably notdestroy them in a preemptive attack, the Soviet Union would haveless incentive to launch a first strike. Thus, crisis stabilitymight not be jeopardized by deployment of mobile-based U.S.counterforce weapons.

Arms control might be complicated by the introduction of amobile-based counterforce weapon such as MX. Such a weapon would

be more difficult to count than silo-based missiles, and thusenforcement of arms control agreements might be more difficult.Proponents of U.S. counterforce capability have argued that evenmobile weapons could be counted at choke-points through whichall deployed missiles would have to pass, such as the entrances tounderground tunnels. Moreover, they argue that a U.S. missilesystem threatening to Soviet silo-based ICBMs would probably forcethe Soviet Union to move to a mobile missile-basing system of

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their own, thus reestablishing a stable situation in which itwould not pay for either side to attack the forces of the other.Opponents of weapon systems such as MX suggest that it would bebetter to avoid such an expensive solution to the ICBM vulnera-bility problem by reaching arms control agreements that limit thecounterforce threat. For example, strict limits on missileflight tests or on the number of ICBMs that could be armed with

multiple warheads might prevent both sides from developing anability to attack each other's land-based missiles. There isdisagreement, however, over whether or not the prospect of MXdeployment would contribute to the negotiation of such an agree-ment, since many believe that ongoing U.S. arms programs providebargaining leverage, while others argue that U.S. restraint wouldbetter contribute to the negotiating process.

It might be better to develop a new mobile ICBM only toimprove survivability and not to enhance U.S. counterforce capa-bility. Such a course would seek to avoid the potentially de-stabilizing aspects of counterforce capability, yet it wouldrespond to the growing vulnerability of silo-based ICBMs. Coun-terforce proponents argue that the counterforce potential of theMX missile would be desirable since the United States might wantto be able to retaliate against Soviet ICBMs remaining after anattack on vulnerable U.S. forces, such as silo-based missilesand nonalert bombers and in-port submarines.

One way to develop a U.S. second-strike counterforce capa-bility without posing a first-strike threat to the Soviet Unionmight be to rely on accurate cruise missiles to counterattackagainst Soviet ICBMs. Since these weapons would take severalhours to reach their targets, they would probably not be seen asfirst-strike weapons. Because of their accuracy, cruise missileswould be very effective against hardened Soviet ICBM silos. Theremay, however, be a possibility of developing air defenses againstcruise missiles, although the Department of Defense believes thatU.S. cruise missile technology will stay ahead of Soviet defensivetechnology. Furthermore, there remains some uncertainty aboutcruise missile accuracy and reliability since this weapon is stillin development.

U.S. Options

Finite Deterrence. A policy of finite deterrence would relyupon a well-hedged threat to retaliate against Soviet cities to

deter nuclear attacks by the Soviet Union, including strikesagainst U.S. strategic forces. In practice, the United States

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would have enough weapons for other forms of retaliation, such asattacks on Soviet conventional military targets. Under a policyof finite deterrence, the United States could procure Trident Imissiles, about 20 Trident submarines, and about 3,000 cruisemissiles for the B-52 force. New counterforce weapons such as MXICBMs, Trident II SLBMs, and large numbers of bomber-launchedcruise missiles would not be required under this policy. A forcefor finite deterrence would cost about $111.2 billion (in fiscalyear 1978 dollars) for investment and operating from fiscal years1979 to 2000.

Slow Counterforce. Under a policy of slow counterforce, theUnited States would add to its base force of Trident submarinesand missiles, B-52 bombers, and Minuteman ICBMs enough cruisemissiles and cruise missile carriers for a counterattack against

Soviet ICBMs. Because bombers would take several hours to reachthe Soviet Union, such a force would provide an ability to carryout a second-strike counterforce attack without posing a first-strike threat to Soviet land-based strategic forces. During theperiod between fiscal years 1979 and 2000, a policy of slowcounterforce would add $14.3 billion (in fiscal year 1978 dollars)to the base force cost of $111.2 billion, for a total costof $125.5 billion.

Prompt Counterforce. A policy of prompt counterforce wouldcall for the procurement of mobile MX ICBMs and/or Trident IISLBMs. These weapons would provide a capability to retaliateagainst Soviet ICBMs within minutes of a Soviet first strike.

Procurement of the MX missile system could also enhance thesurvivability of the land-based force and thus maintain a viableTRIAD. Such a policy would reflect a judgment that a mobilemissile system threatening to the Soviet ICBM force would bestabilizing rather than destabilizing, because mobile missileswould be invulnerable to a Soviet preemptive strike and becausethey would provide a means to respond to, and thus deter, a Sovietcounterforce attack.

During the period between fiscal years 1979 and 2000, pro-curement of the MX system would add $25.2 billion (in fiscal year1978 dollars) to the costs of the strategic forces, for a totalcost of $136.4 billion. A sea-based counterforce capability wouldrequire the procurement of 768 Trident II missiles and 12 extraTrident submarines at a cost of $28.7 billion (in fiscal year 1978dollars), for a total cost of $139.9 billion.

The following table summarizes the costs of the three op-tions.

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SUMMARY OF COSTS OF THREE OPTIONS: BY FISCAL YEARS

(In Millions of Curr ent Dollars)1979 1980 1981 1982 1983

(In Millions ofFY 1978 Dollars)

1979 through 2000

FiniteDeterrence 7,120 8,530 9,110 9,6 00 10 210 111,200

SlowCounterforce

PromptCounterforce

Trident IIOption

7,120 8,530 9,110 9,600 10,210

MX Option 7,330 9,130 10,340 11,430 11,910

7,230 8,410 9,750 11,790 13,020

125,500

136,400

139,900

NOTE: Costs shown do not include all the costs of maintaining the strategicforces. Wot included are the costs of such functions as command,control, and communications; surveillance; and strategic defense; andthe costs of nuclear warheads.

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II

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CHAPTER I. INTRODUCTION

U.S. strategic nuclear forces are charged with the missionof deterring a Soviet nuclear attack on the United States. I/Since defenses against a nuclear attack are both difficult andlimited by the Anti-Ballistic Missile Treaty between the UnitedStates and the Soviet Union, the United States relies upon theability of its strategic forces to carry out a devastating retali-atory strike against Soviet cities to deter a Soviet attack. U.S.forces are designed to be capable of carrying out this assureddestruction mission after having absorbed a well-coordinatedsurprise Soviet strike against them.

In order to hedge against the failure or destruction ofone part of its nuclear force, the United States maintains a mixedforce of long-range bombers, land-based intercontinental ballisticmissiles (ICBMs), and submarine-launched ballistic missiles

(SLBMs), known collectively as the TRIAD. By diversifying theforce among three parts, each of which has different vulnerabili-ties, a Soviet nuclear attack on U.S. strategic forces, usuallyreferred to as a counterforce attack, is made more difficult.

In recent years, however, concern has grown that one elementof the U.S. strategic TRIAD, land-based ICBMs, may become vulner-able to a disarming first strike by an increasingly capableSoviet force. Using a fraction of their ICBM force, the os-tulated Soviet attack would destroy large portions of U.S.missiles in their hardened silos. Simultaneous attacks on U.S.Strategic Air Command (SAC) bases and submarine ports woulddestroy bombers not on alert and missile-carrying nuclear sub-marines (SSBNs) not at sea. At the same time, the existence of alarge Soviet reserve force capable of destroying U.S. cities woulddeter a U.S. counterstrike against Soviet cities and thus leaveU.S. leaders with few attractive retaliatory options.

I/ In principle the strategic nuclear forces are also designed todeter attacks by other countries, but for the foreseeablefuture the need to deter attack by other countries willnot significantly increase U.S. orce requirements.

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Considerable controversy has surrounded both the issueof U.S. vulnerability to a Soviet counterforce attack and thequestion of what the Soviets might hope t o gain from such an

attack. Many observers believe that the United States faces asignificant, and growing, Soviet counterforce threat and that adeterrence doctrine that relies upon retaliation against Sovietcities would provide American leaders with few credible responsesto such an attack. They believe that to deter a Soviet counter-force attack U.S. strategic forces must be able to carry out acounterattack against the Soviet ICBM force, since the threat toretaliate against Soviet cities might not be credible as long asU.S. cities remain intact.

On the other side are critics of any U.S. attempt to planand build forces for counterforce wars, those confined to eachside's nuclear forces. These critics believe that a Sovietnuclear attack confined to strikes against U.S. strategic forceswould inflict so much damage on U.S. cities and population thatthe United States would be expected to respond with its survivingSLBMs and alert bombers and that this expectation should deter anybut the most desperate Soviet leadership from attempting such astrike. Furthermore, many believe that U.S. preparations to fightcounterforce battles only make nuclear war more likely to occurbecause U.S. weapons capable of counterattacking against SovietICBMs might appear to pose a first-strike threat to Soviet stra-tegic forces and thus cause a Soviet leadership facing a seriousinternational crisis to launch a preemptive attack.

Over the next several years the Congress will face a numberof important force procurement issues that depend criticallyon judgments about the degree and signficance of U.S. strategicvulnerability to Soviet counterforce capability and the properresponse to such a development. By the mid-1980s, when U.S.silo-based missiles will probably become increasingly vulnerableto Soviet attack, Trident nuclear submarines and Trident I sub-marine-launched missiles will be entering the force, and cruisemissiles will be deployed on B-52 bombers. Although these sys-tems will probably be sufficient for retaliation against Sovietindustry, leadership targets, and general purpose militaryforces, 2 / many analysts have expressed concern about the pos-

_ 2 / For an examination of the second-strike capabilities ofU.S. forces against Soviet industry and general purposemil itar y forces, see the forthcoming companion paper onretaliatory issues.

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sibility that improved Soviet ICBMs will enable the Soviet Unionto launch a counterforce strike against U.S. silo-based ICBMs,while the United States could not respond in kind. If the Con-gress wishes to maintain strategic forces capable of carrying outa second-strike counterforce attack against Soviet ICBMs, the pro-curement of new and more sophisticated weapons would be required.

Judgments about the significance of Soviet counterforcecapability and the need for a similar U.S. capability will, to agreat extent, determine the pace of development and magnitude ofprocurement of MX mobile missiles, Trident submarines, Trident IImissiles, cruise missiles, and cruise missile carriers beyondthe existing B-52 force.

The MX missile, a more accurate, more powerful, and po-tentially mobile ICBM now in the research and development (R&D)stage and available for deployment by the mid-1980s, will providea future option to reduce the vulnerability of land-based mis-siles, and at the same time substantially upgrade the counterforcepotential of the U.S. nuclear arsenal.

The large missile tubes of the Trident submarines now underconstruction will be capable of housing a larger and more accurateTrident II missile. This missile, which could be developed by themid-to-late 1980s, offers an alternative means of developing acapability to attack Soviet ICBM silos in a second strike.Since the assignment of submarine-launched missiles to the coun-terforce role would, however, require the procurement of addi-tional submarines beyond those needed for retaliation againstSoviet cities, the present Trident building rate of three sub-marines every two years would have to be accelerated in the nearfuture.

The U.S. cruise missile, guided to its target by a terrain-matching guidance system that is asserted to be extremely ac-curate, will provide another means to enhance the counterforcecapability of U.S. strategic forces. If the Congress decides toprocure extra cruise missiles for the counterforce task, addi-tional carriers, such as wide-bodied aircraft, would be required.

Decisions about these programs to augment and modernizeU.S. strategic nuclear forces in the mid-to-late 1980s will dependupon several basic questions:

o Under what circumstances might the Soviets be tempted tostrike one vulnerable element of the U.S. TRIAD, knowingthat a large retaliatory force would survive?

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o Should the United States develop the capability toretaliate against Soviet ICBMs?

o Is the best response to increasing ICBM vulnerabilitya shift to more survivable basing systems or the develop-ment of a similar threat to Soviet ICBMs?

o How might the Soviet Union react to a threat to theirICBMs, and would this reaction be desirable or undesir-able?

Chapter III of this study examines the projected vulner-ability of U.S. strategic forces, especially the ICBM portion ofthose forces. Chapter IV deals with the arguments for and againstthe development of U.S. counterforce capability.

Before examining the issues of U.S. strategic vulnerabilityand counterforce capability, however, it is useful to consider thequestion of Soviet motives in launching a counterforce attack.Only in this context is it possible to develop general criteriafor judging the success or failure of a given Soviet strategy andwhat may be required to deter it.

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CHAPTER II. COUNTERFORCE STRATEGIES

In any discussion of counterforce exchanges it should alwaysbe remembered that a major nuclear war would be a catastrophe of

unprecedented proportions; starting or risking such a war would bea desperate act undertaken only under great stress and in theface of a perceived threat to very important values. Even a warconfined strictly to attacks on nuclear forces would likely causemillions of deaths and great damage and disruption on both sides.In addition, neither side could be certain that a limited nuclearexchange would remain limited and not eventually escalate toall-out attacks that would cause the deaths of tens of millions.In fact, it is difficult to imagine the circumstances in whichinitiating a nuclear war would be the least miserable optionfacing national leaders. Precisely because a nuclear war would besuch a catastrophe, however, prudence demands that the factorsthat might contribute to its occurrence be carefully considered.

In general, there are at least three Soviet counterforcestrategies that have been postulated. They are:

o An attack on the U.S. ICBM force designed to reduceU.S. options in a limited nuclear war.

o An attack on U.S. strategic forces designed to shiftdecisively the balance of nuclear power in favor of theSoviet Union.

o An attack on U.S. strategic forces designed to limitdamage to the Soviet Union in an all-out nuclear ar.

In recent years the Department of Defense (DoD) has concen-trated on the first of these strategies, expressing concern that asuccessful Soviet counterforce strike against land-based missileswould endanger the ability of the United States to execute flex-ible options short of all-out retaliation. The superior accuracyand command and control capability inherent in a land-basedsystem, capabilities that might be important for strikes againstSoviet military forces involved in a war in Europe or other

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areas of U.S. treaty commitments, would be lost in such anevent. I/ Leaving aside the controversy surrounding the issue oflimited nuclear options and the desirability of maintaining forcesdesigned for such contingencies, there are several questions thatcan be raised about the scenario postulated by the Defense Depart-ment.

For one thing, it is unclear that the United States wouldremain interested in the execution of flexible and controlledresponses after having absorbed a large-scale nuclear attack onU.S. ICBMs that killed millions of Americans. In any case, giventhe existence of thousands of nuclear weapons in surviving ICBMs,bombers, and submarines, as well as tactical missiles and air-craft, the United States would retain many retaliatory options,since surviving forces would be capable of carrying out strikesagainst Soviet conventional forces or important isolated economictargets. Many analysts believe, however, that U.S. forces shouldbe capable of carrying out a counterattack against Soviet ICBMsilos. A requirement that U.S. strategic forces be able toperform such a second-strike counterforce mission might call forthe procurement of additional, and more sophisticated, U.S.nuclear weapons.

Others have suggested that the Soviet Union might be moti-vated to strike U.S. strategic forces in order to shift decisivelythe balance of power in their favor. A counterforce attack withthis goal in mind would be designed to destroy such a largeportion of U.S. forces with such a small expenditure of Soviet

I/ Defense Secretary Schlesinger summarized this concern:

Since both we and the Soviet Union are investing somuch of our capability for flexible and controlledresponses in our ICBM forces, these forces couldbecome tempting targets, assuming that one or bothsides acquire much more substantial hard-target killcapabilities than they currently possess. If oneside could remove the other's capability for flexi-

ble and controlled responses, he might find ways ofexercising coercion and extracting concessionswithout triggering the final holocaust.

(Annual Defense Department Report, FY 1976 and FY 197T,page I1-4.)

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force that the Soviets would gain strategic superiority so massivethat the extreme asymmetry in the destruction that the two sidescould inflict on one another would deter the United States fromusing its inferior force in retaliation. In this case, Americanleaders might be left with few response options, and U.S. forcesmight fail to deter a Soviet first strike. To deter a Sovietcounterforce attack designed to shift the balance of nuclear

power, many analysts believe that the United States must maintainsurvivable forces large enough to prevent a massive Soviet advan-tage in the ability to inflict damage. Others believe that theU.S. forces should be capable of counterattacking against Sovietstrategic forces remaining after a counterforce strike against theUnited States. In this way, the United States might be able toredress an imbalance of power resulting from a Soviet firststrike.

A third possible Soviet counterforce strategy would involveattacks on U.S. nuclear forces for the purpose of limiting thedamage that the United States could inflict on the Soviet Union inan all-out nuclear war. Obviously, a Soviet leadership consid-ering such an attack would have to be convinced that circumstanceswere so desperate that nuclear war was imminent. In this case, bystriking first, the Soviets might be able to destroy a largepercentage of the U.S. nuclear force, thus making the outcome of anuclear war less catastrophic for the Soviet Union than it other-wise would have been. Deterrence of a damage-limiting strikerequires that U.S. nuclear forces must be able to survive aSoviet counterforce attack against them and then carry out adevastating retaliatory attack against Soviet cities. U.S. forcescapable of retaliating against Soviet nuclear forces would not berequired in this case. The surviv abili ty of U.S. forces isexamined in Chapter III of this study.

Those who believe that the Soviet Union might be temptedto attack U.S. strategic forces for the purpose of reducingAmerican options or shifting the balance of power suggest thatdeterrence requires not only forces capable of destroying Sovietcities but also weapons designed to counterattack against Sovietnuclear forces. Opponents of such a second-strike counterforcepolicy suggest that there is a dilemma involved in the procurementof U.S. counterforce weapons. They believe that a U.S. forcelarge enough to retaliate against Soviet nuclear forces in asecond strike would, by definition, pose a significant first-strike threat to the Soviet Union. Furthermore, this threat mightdangerously destabilize the strategic balance and prov ide an

incentive for a Soviet first strike. Chapter IV focuses on thequestion of U.S. second-strike counterforce capability and theassociated doctrine.

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CHAPTER III. U.S. STRATEGIC VULNERABILITY

U.S. ICBM VULNERABILITY

In the 1960s, silo-based Intercontinental Ballistic Missiles

(ICBMs) were thought to be essentially invulnerable to a firststrike. In order to destroy such a target, an attacker would haveto fire a missile of his own at each enemy missile site. Sincemany of the attacker's missiles would fail to function properly ormiss their targets, it was inevitable that the attacker would usemore weapons than he could possibly destroy. Thus, given roughlyequal forces, an attack under such circumstances would be aself-disarming act.

In recent years, howeve r, technological advances havedramatically altered this picture. The crucial event was thedevelopment of Multiple Independently Targetable Reentry Vehicles,or MIRVs. With missiles that carry more than one warhead, an

attacker can potentially destroy mor e than one enemy missilefor each one he uses. If the U.S. and Soviet ICBM forces wereconstrained to be of roughly equal size, either by arms controlagreements or by cost considerations, then an attacker usingMIRVed missiles might be able to destroy a large part of the otherside's ICBMs while expending only a fraction of his own force.

The United States developed and deployed the first MIRVedICBM, the three-warhead Minuteman III missile. In 1975 the SovietUnion began deployment of its own MIRVed ICBMs, the SS-17, SS-18,and SS-19. This coupling of traditionally large Soviet missileswith MIRV technology has been a particularly disquieting event,because the power of these missiles makes possible the delivery oflarge numbers of warheads. The SS-18, for example, can delivereight to ten warheads, thus creating the possibility that eachSS-18 might destroy several U.S. silo-based missiles.

Even with the deployment of MIRVed missiles, the actualvulnerability of ICBM silos to a counterforce strike is determinedby the interaction of several other factors: the hardness of thetarget; the accuracy, explosive power, and reliability of theattacking missile; and the tactics used in the attack. For ex-ample, a one megaton warhead, typical of Soviet weapons, delivered

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...Uffllllli JL_

by a reliable missile with circular error probable (CEP) I/ of1,200 feet (0.2 run) would have less than a 50 percent chance ofdestroying a silo hardened to withstand 2,000 pounds per square

inch (psi). If accuracy could be improved to 600 feet (0.1 nm),the same one megaton weapon would have almost a 90 percent chanceof destroying the same target. A missile accurate to 600 feetbut with warhead yield of only 20 kilotons (equivalent to the bombdropped on Hiroshima), however, would have less than a 20 percentchance of destroying a target hardened to 2,000 pounds per squareinch. Thus, an appropriate combination of accuracy and warheadyield is needed for an effective counterforce capability.

U.S. missiles are generally believed to be more accurate thantheir Soviet counterparts, but in recent years the Soviet Unionhas been making great strides in the field of guidance technology.Since the warhead yields of the current generation of Soviet ICBMsare already very large, improvements in missile accuracy will bethe major driving force behind growing Soviet counterforce capa-bility.

Uncertainties of Attack Effectiveness

A very significant consideration for attack planning is thegreat uncertainty surrounding the actual accuracy of any givenguidance technology. This uncertainty results in part from thelimited number of tests a missile system undergoes to verify itsaccuracy potential. Gaining high confidence in estimates of amissile CEP would require a large number of tests for each missileand for each change in its guidance system. Such testing isconstrained, however, by the limited resources that can be devotedto the very expensive task of missile testing. Moreover, actualoperational performance can be degraded by variable atmosphericconditions and small perturbations in the earth's gravitational

I/ The measure most commonly used to describe the accuracy of aballistic missile is known as circular e r r o r probable (CEP).This is the radius , centered about the intended target,

that forms a circle within which 50 percent of the warheadswill land.

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field. 2/ As a result, actual CEPs can only be estimated within afairly large range of uncertainty, and any assessment of thedamage that an attack can be expected to cause must take intoaccount the uncertainties surrounding these operational ac-curacies.

Although missile accuracy is perhaps the most important

source of uncertainty about the actual results of a counterforceattack, similar uncertainty surrounds estimates of warhead yield,missile and warhead reliability, and silo hardness. Again, muchof this uncertainty results from the limited amount of test data.In addition to the expense of missile and warhead tests, otherconstraints prevent the gathering of complete knowledge aboutthe performance of weapon systems. For example, treaty restric-tions on atmospheric detonations prevent actual testing of silohardness. As a result, no one can know for sure how resistantthese shelters will be to the various effects of nuclear detona-tions .

Fratricide and Counterforce Tactics

The operational performance of weapons is not the only sourceof uncertainty about the results of a counterforce attack. Inrecent years analysts have come to recognize an additionalattack constraint resulting from the effects of nuclear detona-tions on warheads entering an area where previous explosions havetaken place. This phenomenon, known as fratricide, could causethe destruction of weapons used in a large-scale attack on missilefields, and it therefore places severe restrictions on counter-force tactics that involve the targeting of more than one warheadon each silo. In fact, most analysts believe that no more thantwo warheads could be exploded in the neighborhood of each enemy

2 / American missiles are typically fired over the Pacific Oceanat Kwajalein Island in the Marshall Islands. While such testsmay give weapons designers precise knowledge of the gravita-tional forces that this portion of the earth exerts on bal-listic missile flight, they are not necessarily accurateindicators of how a missile fired over the Arctic at theSoviet Union would perform. Presumably the Soviet Union facessimilar uncertainty about possible accuracy degradationbecause of unpredictable guidance errors of this sort. As aconsequence, an attacker could never be sure that his missileswould perform in an actual counterforce attack as test datawould lead him to believe.

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missile silo. Even a two-on-one attack would be difficult,since first-wave warheads would have to be exploded severalhundred feet above the target in order to avoid throwing lethal

ground debris into the air, while second-^wave warheads (targetedto explode on the ground) would have to enter the area withsplit-second timing in order to avoid destruction by the nucleareffects of first-wave warhead detonations.

It is possible that no more than one warhead could besuccessfully exploded over each target. Other nuclear effects,such as intense heat and dust clouds, could be lethal to subse-quent warheads even if first-round weapons were burst above thesurface in order to avoid the throwing of ground debris into theair. 3/ An attacker who accepted this view would fire two war-heads (both programme^ to detonate on ground contact) at eachenemy silo only to insure against the possibility that the firstone proved to be unreliable and either failed to reach the area ofthe target or to explode. 4/ If no more than one nuclear warheadcould be exploded in the neighborhood of each target, an attackerwould be better off not to try for two detonations, since such anattempt requires that less accurate, less destructive airbursts beused in the attack. 5/

3/ For an unclassified discussion of fratricide, see Joseph J.McGlinchey and Jakob W. Seelig, Why ICBMs Can Survive ANuclear Attack, Air Force Magazine, September 1974.

4/ More than two warheads could be fired at each silo, but thesmall additional probability that at least one warhead wouldreach each target would probably not be worth the cost interms of expended attacker weapons.

5 / The penalty for an unsuccessful attempt to explode two war-heads over each silo can be quantified by examining the casein which fratricide proves to be unavoidable and first-waveairburst warheads destroy second-wave groundburst warheads.Expected damage to the ICBM force in this case would be 44percent for an attack with SS-18 missiles accurate to 1,200feet (assuming 20 percent height of burst error for airburst

warheads, and assuming that second-wave groundburst warheadsreach 25 percent of the silos due to first^wave failures).This 44 percent damage expectancy compares with 54 percent forthe case of two groundbursts (one explosion). The potentialloss of 10 percent damage expectancy compares with a potentialgain of 8 percent if an attempt to explode two warheads overeach silo were successful (see Appendix B).

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Uncertainties about fr atricide will probably never besettled. For one thing the prohibition on atmospheric testingprevents real world evaluation of a modern warhead's ability towithstand the various effects of a nuclear explosion. In light ofthe penalties that would be paid for an unsuccessful attempt toavoid fratricide, an attacker would probably have to make theconservative assumption that insuring against missile and warheadunreliability is the best tactic available. On the other hand,consideration of more ambitious attacks that successfully detonatetwo warheads in the area of each target does serve to provide anupper bound for the damage that a Soviet counterforce strike mightcause. 6/

A third counterforce tactic attempts to program two warheadsto detonate in the neighborhood of each target while at the sametime reprogramming spare missiles to replace those that fail inthe early portions of flight. In a two-on-one attack that at-tempts to explode two warheads in the area of each target, repro-gramming for reliability would be a particularly demanding task,since the warheads from replacement missiles would have to arriveon target at the same time as those of the failed missiles inorder to avoid fratricide. For this reason, an attack that couldget two successful explosions in the neighborhood of each targetand reprogram failed missiles is probably the worst scenario thatU.S. missiles could possibly face.

U.S. ICBM Vulnerability in the Mid-1980s

As we have seen, a successful counterforce attack requires aforce of MIRVed ICBMs that combines high accuracy and warheadyield. Until recently, the Soviet Union did not possess such aforce. The bulk of the Soviet ICBM force consisted of single-warhead SS-9s and SS-lls that are reportedly capable of accuraciesno better than about one to one-half of a nautical mile. 7/

6/ More than two warheads might be exploded in the area of eachsilo if the attacker waited for an hour or more for dustclouds to dissipate. A delay of this length would, however,greatly increase the opportunity for the victim to launch hissurviving missiles.

7/ See Thomas J. Downey, How to Avoid Monad and Disaster,Foreign Policy, Fall 1976.

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By the mid-1980s, the Soviets should complete deployment of anew generation of MIRVed ICBMs, the SS-17, SS-18, and SS-19 withfour, eight, and six warheads respectively. This modernization

program will apparently not be significantly constrained by a SALTII treaty, since the Soviets will probably be allowed to replaceall their large SS-9 ICBMs with MIRVed SS-18 missiles and sincevery high limits on MIRVed ICBMs will be allowed. 8/ One un-classified estimate of what Soviet strategic forces might looklike by 1985 is presented in Table 1. For comparison, estimatesof the size and structure of U.S. forces are presented in Table 2for both 1977 and the mid-1980s.

Many observers have expressed concern that a Soviet ICBMforce consisting of thousands of multiple warheads, with thecombination of high yield and improved accuracy shown in Table1, would pose a significant threat to the U.S. ICBM force. With

the aid of computer missile exchange simulations based on theestimates presented in Tables 1 and 2, it is possible to examinein more detail the exact nature of this threat. 9/

An attacker planning a counterforce strike would have anincentive to program both warheads fired at each enemy missilesilo to detonate on ground contact. Although such a tactic wouldprobably eliminate any chance to get two detonations in theneighborhood of each target, it would greatly increase the oddsthat every enemy silo would suffer the effects of a nuclearexplosion, and it would avoid the use of less accurate, lessdestructive airbursts. A Soviet attack that exploded no morethan one warhead on each target (but fired two), using 264 eight-warhead SS-18s, all accurate to 1,500 feet, against 1,054 U.S.ICBM silos, 10/ would be expected to destroy about 40 percent

8/ See Major Concessions By U.S. and Soviet on Arms Reported,New York Times, October 11, 1977, p. 1.

9/ The SNAPPER Force Exchange Model developed for the Air Forceby the Rand Corporation has been used to calculate attackresults. For a detailed description of this model see

Appendix A.10/ Assuming Minuteman silo hardness of 2,000 pounds per square

inch and Titan hardness of 550 pounds per square inch.See MX Deployment Urged for Parity, Aviation Week andSpace Technology, December 5, 1977, p. 13.

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of the land-based missile force. This would leave intact 60percent of the U.S. ICBM force, consisting of over 600 missiles,1,200 warheads, and 600 equivalent megatons, ll/ Even if Sovietmissile accuracies could be improved to 1,200 feet, only about 55percent of U.S. ICBMs would probably be destroyed, leaving 45percent of the land-based force, or over 450 missiles, 950 war-heads, and 450 equivalent megatons. 12/

These results indicate the number of U.S. missiles that canbe expected to survive a Soviet attack, given specific assumptionsabout the performance of the weapon systems involved in theattack. As discussed in prev ious sections, a great deal ofuncertainty surrounds estimates of these parameters. Therefore,an attacker would have to consider the degree of confidence thathe could have in the results of an attack, as well as the bestguess about those results. If the values of CEP, warhead yield,reliability, and target hardness are all allowed to vary withinreasonable limits, the range of results that would bound theactual, unknown result with 90 percent confidence can be de-termined. For an attacker concerned about the catastrophic

consequences of failure, a reasonably narrow confidence intervalwould obviously be an important consideration in the decision toattack or not. In the attacks described above, the number ofsurviving U.S. ICBMs can vary, with 90 percent confidence, from 70percent to 45 percent after an attack by Soviet missiles theoreti-cally capable of 1,500-foot accuracies. In other words, there isa 5 percent chance that 70 percent of the U.S. ICBMs, ratherthan 60 percent, would survive the Soviet attack, and a 5 percent

ll/ Equivalent megatonnage is a commonly used measure of theurban area destructive power of a nuclear weapon that ac-

counts for the fact that area destructive power does notincrease proportionately with increases in yield* It is ex-pressed by the relationship EMT = N multiplied by Y to the2/3 power, w here N is the number of weapons of yield Y.

12/ If the Soviets could succeed in exploding two warheads overeach silo, they could destroy about 50 percent of the U.S.ICBM force, assuming a 1,500 ft. Soviet CEP. A Soviettwo-on-one attack with missiles accurate to 1,200 feet wouldbe expected to destroy about 60 percent of U.S. ICBMs. Iftwo warheads could be exploded over each U.S. silo and earlymissile failures could be reprogrammed, damage to the U.S.ICBM force would be expected to be; 55 percent, assuming a

1,500 ft. Soviet CEP, or slightly less than 70 percent, as-suming 1,200 ft. CEP. For detailed results, see Appendix B.

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TABLE 1. ESTIMATED SOVIET STRATEGIC NUCLEAR FORCES, 1985

Launcher

SS-11SS-17SS-18SS-19SS-16

Total ICBMs

SS-N-6 )

SS-N-8 J

SS-N-17)

SS-N-18J

TotalSLBMs

BearBison

(Backfire)

TotalBombers

GrandTotal

Warheads Per

Number a/ Launcher b /

33 0 1200 430 8 8500 6

60 1

1,398

60 0 1

300 3

900

100 140 1

(250) (2)

140(390)

2,438(2,688)

TotalWarheads

330800

2,4643,000

60

6,654

600

900

1,500

10040

(500)

140(640)

8,294(8,794)

Yield in

Megatons

1.50.61.50.81.0

1.0

0.2

205

(0.2)

Total

c/ Megatons

495480

3,6962,400

60

7,131

600

180

780

2,000200

(100)

2,200(2,300)

10,111(10,211)

CircularEquivalent Error

Megatons Reliability d/ Probable e/

432 0.70 3,000 ft.560 0.75 1,500 t.

3,228 0.75 to2,580 0.75 1,200 t.

60 0.75

6,860

600 0.70 6,000 ft.

306 0.70 3,000 ft.

906

740116

(170)

856(1,026)

8,622(8,792)

(continued)

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a

TABLE l. (Continued)

SOURCES:

a. Number of SS-18s and total number of SS-17s and SS-19s from testimony of General Alton Slay, in Militar y Postureand H.R. 11500, Hearings before the House Ar med Services Committee, 94:2 (1976), Part 5, p. 288. Ratio of SS-19s toSS-17s assumed same as at present. Number of MIRVed SLBMs assumes 1,320 MIRVed ballistic missile limit. Numbersof Bears and Bison from General George S. Brown, United States Military Posture for FY 1978, p. 18. Number ofBackfire assumes annual production of 25 (see International Institute for Strategic Studies (IISS), The MilitaryBalance, 1977-78 (London: 1977), p. 4.).

Total number of Soviet delivery vehicles shown exceeds any likely SALT II agreement. Given a limit of 2,200 stra-tegic delivery vehicles, the Soviets would have to retire about 200 launchers, probably older SS-11 ICBMs and Bearand Bison bombers. With a MIRVed ICBM ceiling of 800, 200 fewer SS-17s and SS-19s would probably be deployed.SS-18 deployment would not necessarily be affected.

b. Number of ICBM warheads from Donald H. Rumsfeld, Annual Defense Department Report, Fiscal Year 1978, p. 62. SLBMwarhead figures from General George S. Brown, United States Military Posture for FY 1978, p. 16. Bomber figures fromProjected Strategic Offensive Weapons Inventories of the U.S. and U.S.S.R., Congressional Research Service, March24, 1977, p. 85.

c. Warhead yields from MX Deployment Urged for Parity, Aviation Week and Space Technology, December 5, 1977, pp.14-15, and Jane's Weapon Systems, 1977, pp. 10-12. Bomb yields from Projected Strategic Offensive Weapons Inven-tories of the U.S. and USSR, p. 95.

d. Obtaining missile reliability greater than 80 percent is believed to be a very difficult task (see Alber t C. Hall, The Case for an Improved ICBM, Astronautics and Aeronautics, February 1977, p. 29). Soviet missiles are generallyconsidered to be less reliable than their U.S. counterparts.

e. Although official estimates of Soviet missile accuracies are classified, va rious public sources provide an unclassi-fied consensus estimate of 1,500 ft. (0.25 nm) CEP for the new generation of Soviet ICBMs. See U.S. Missiles SeenVulnerable by Early 1980s, Washington Post, September 18, 1977, p. A6. In addition, one official statement addscredence to this estimate. In an appearance before the Senate F oreign Relations Committee in 1974, Secretary ofDefense James Schlesinger testified: We have some information that the Soviets have achieved, or will soon achieve,accuracies of 500 to 700 meters with their ICBMs. These figures may be a little optimistic, but that would representabout a fourth to a t h i r d of a nautical mile. (Briefing on Counterforce Attacks, Hearing before the Subcommittee onArms Control, International Organizations and Security Agreements of the Senate Foreign Relations Committee, 94:1(September 11, 1974), p. 10.) In addition, defense officials have alluded to the possibility of further improvementsi n accuracy with continued testing of the current generation of missiles. (See Department of Defense Authorization,Fiscal Year 1978, Hearings before the Senate Armed Services Conroittee, 95:1 (April 1977), Part 10, p. 6869.) There-fore, accuracy upgrade to 1,200 ft. (0.2 nm) is also considered. See MX Deployment Urged for Parity, Aviation Weekand Space Technology, December 5, 1977, pp. 14-15.

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TABLE 2. ESTIMATED U.S. STRATEGIC NUCLEAR FORCES

Minuteman IIMinuteman IIITitan II

Total ICBMs

(Present Force)

LauncherWarheads

Number per LauncherTotal

WarheadsYield inMegatons

TotalMegatons

EquivalentMegatons Reliability

CircularE r r o r

Probable

450550

54

1,054

4501,650

54

2,154

1.00.179.0

450.0280.5486.0

1,216.5

450512232

1,194

0.800.800.75

1,800 ft.700 ft.

3,000 ft.

PolarisPoseidon

Total SLBMs

B-52 G/H

B-52D

FB-111

Total Bombers

Grand Total

160496

656

255

75

60

390

2,100

110

(4 SRAM

(4 Bombs4 Bombs

(2 SRAM

(2 Bombs

1604,960

5,120

1,020

1,020300120

120

2,580

9,854

0.60.04

0.2

1.01.00.2

1.0

96198

294

204

1,020300

24

120

1,668

3,178.5

163 0.80 3,000 ft.595 0.80 1,500 ft.

758

347

1,020300

41

120

1,828

3,780

SOURCES: There is fairly wide agreement among various unclassified estimates of U.S. nuclear forces. For ICBM and SLBMfigures, see Thomas J. Downey, "How to Avoid Monad and Disaster, Foreign Policy, Fall 1976; Statement ofthe Honorable Robert L. Leggett, Vladivostok Accord; Implications to U.S. Security, Arms Control, and WorldPeace, Hearings before the Subcommittee on International Security of the House Committee on InternationalRelations, 94:1 (June-July 1975), pp. 8-14; and Kosta Tsipis, The Accuracy of Strategic Missiles, ScientificAmerican, July 1975, p. 190. Minuteman III CEP of 700 ft. (see "U.S. Plans 'Cold-Launch 1 ICBMs, Aviation Weekand Space Technology, February 4, 1974, p. 14) assumes the more accurate MK-12A warhead not yet deployed. Forbomber estimates, see Archie L. Wood, Modernizing the Strategic Bomber Force Without Really TryingA CaseAgainst the B-l, International Security, Fall 1976, and Alton H. Quanbeck and Archie L. Wood, Modernizing theStrategic Bomber Force (The Brookings Institution, 1976), p. 36.

(continued)

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TABLE 2 . (Continued)

(Mid-1980s Force)

1

E

Launcher

Minuteman IIMinuteman III

(with MK-12A)Titan II

Total ICBMs

PoseidonPoseidon C-4Trident I

Total SLBMs

B-52 G/H

B-52CM

FB-111

Total Bombers

Grand Total

Number

450550

(550)54

1,054

336160240

736

165

165

60

390

2,180

Warheads Totalper Launcher Warheads

(6

4

20(2

(2

13

(3)1

1088

SRAM

BombsALCMSRAM

Bombs

1(1

2

311

6

3

5

13

450,650,650)

54

,154

,360,280,920

,560

990

660,300120

120

,190

,904

Yield inMegatons

1.0.

(0.9.

0.0.0.

0.

T_L

0.0.

1 .

01735)0

041010

2

f~ \\

22

0

TotalMegatons

450.0280.5

(572.5)486.0

1,216.5(1,508.5)

134128192

454

198

660660

24

120

1,662

3,332.5

(3,629.5)

CircularEquivalent Error

Megatons Reliability Probable

450 0.80 1,800 t.512 0.80 700 ft.

(825) (0.80) (600 ft.)232 0.75 3,000 ft.

1,194(1,507)

403 0.80 1,500 t.282 0.80 1,500 t.422 0.80 1,500 ft.

1,107

337

6601,122 300 ft.

41

120

2,280

4,581

(4,894)

SOURCES: MK-12A y ield from Cruise Missile Halt Considered, Aviation Week and Space Technology, May 23, 1977, p. 19.Lower Minuteman III CEP assumes that MK-12A warhead is more accurate than older MK-12 warhead. Trident Imissile estimates from "New Propellent E valuated for Trident Second Stage, Aviation Week and Space Tech-nology, October 13, 1975, p. 15. Cruise missile yield from ICBM, Guidance Curbs Alarm Planners, AviationWeek and Space Technology, July 11, 1977, p. 17. Cruise Missile CEP from Kosta Tsipis, Cruise Missiles,Scientific American, February 1977, p. 29. Cruise missiles assumed carried by 75 B-52Ds and 90 B-52Gs.

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L

chance that only 45 percent would survive. If Soviet missileswere theoretically accurate to 1,200 feet, there would be a 5percent chance that 60 percent of the U.S. ICBM force, rather than

45 percent, would survive, and a 5 percent chance that only 30percent would survive. 13/

Unless the Soviet Union can make dramatic improvements in itsmissile accuracies, it would appear that the generation of MlRVedICBMs now being deployed could not deliver a decisive blow to theU.S. Minuteman force. Even if missile accuracy could be improvedto 1,200 feet, the Soviets could probably destroy no more than 40to 60 percent of the U.S. ICBM force. In addition, damage of thismagnitude would be a risky prospect, since the operationalperformance of weapon systems is subject to many uncertainties.

U.S. ICBM Vulnerability in the Mid-to-Late-1980s

It has been repsrted that the Soviet Union is developingfour new ICBMs. 14/ These missiles are apparently in the pre-flight phase of development and should be ready for deployment bythe mid-1980s. 15/ Former Chief of Naval Operations, Elmo R.Zumwalt, has reported that component testing of these missiles hasbeen observed. 16/ This would place their development at aboutthe same stage as that of the U.S. MX missile.

Although little information about the characteristics ofthese new missiles is available in the public record, it isbelieved that improved accuracy is a primary Soviet goal. There-fore, as an approximation of the future threat to U.S. land-basedmissiles, it is useful to examine the case of a Soviet attack

13/ See Appendix B for attack outcome variations.

14/ See speech of Secretary of Defense Harold Brown beforethe National Security Industrial Association, reported in Brown Sees Buildup by Soviets in Missiles, New York Times,September 16, 1977, p. 9.

15/ Department of Defense Authorization, Fiscal Year 1978,Hearings before the Senate Armed Services Commitee, 95:1(1977), Part 10, pp. 6859-60.

16/ Elmo R. Zumwalt, An Assessment of the Bomber-Cruise MissileControversy, International Security, Summer 1977.

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using a missile similar in payload and yield to the SS-18 butcapable of accuracies of 900 to 600 feet (0.15 to 0.10 nm). IT/

With accuracies as good as those assumed for the next genera-tion of Soviet missiles, the ability to avoid fratricide andexplode two warheads in the area of each target becomes insignifi-cant since single detonations would produce high damage probabili-

ties. With extremely accurate missiles, second warheads wouldneed to be fired only to improve the odds that each enemy missilesilo would come under attack by at least one weapon. For example,a Soviet attack using missiles accurate to 600 feet that programstwo groundbursts (one explosion) per target in order to insureagainst missile and warhead unreliability would be expected todestroy over 90 percent of the U.S. ICBM force, leaving a land-based force of less than 100 missiles, 200 warheads, and 100equivalent megatons. 18/

Although an attack that plans for only one explosion pertarget is a much less risky tactic, unpredictable variations inthe performance of weapon systems can still result in a range of

attack outcomes. In fact, for the case of c i n attack with missilestheoretically capable of accuracies of 600 feet, the range ofoutcomes can vary, with 90 percent confidence, from 25 percent to5 percent surviving U.S. ICBMs. Thus, the Soviet leadership wouldhave to consider the prospect that there would be a 5 percentchance that 250, rather than 100, U.S. ICBMs would be availablefor retaliation.

In short, while an attempt at a disarming strike againstsilo-based ICBMs would be clearly a risky and unprofitable stra-tegy with missiles accurate only to 1,2:00 feet or more, an attackwith weapons accurate to 600 feet or less might be able to destroyover 90 percent of the land-based U.S. strategic deterrent. Eventhis latter case is risky, however, because of the range ofuncertainty in the outcomes. In addition, land-based ICBMs areonly one element of the TRIAD, and important retaliatory capa-bilities would survive in the bomber and submarine forces evenafter a highly successful attack on ICBMs. In order to assess

17/ Defense Department officials have stated that the achievementof extreme accuracies must await the next generation ofSoviet ICBMs. See Senate Armed Services Committee, Depart-ment of Defense Authorization, Fiscal Year 1978, Part 10, pp.

6860, 6866-67.18/ For detailed results, see Appendix C.

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the profitability of a successful counterforce strike against U.S.ICBMs, it is necessary to examine the vulnerability of the othertw o elements of the U.S. T R I A D , submarine-based missiles andlong-range bombers.

U.S. BOMBER VULNERABILITY

Since the United States maintains about half of its equiv-alent megatonnage in its bomber force, a damage-limiting strikeby the Soviet Union that held out any hope of success would haveto include attacks on U.S. -52 and FB-111 bombers. An attackerseeking to minimize the destruction that this force could inflictwould have two separate opportunities to stop U.S. bombers.First, surprise attacks on Strategic Air Command (SAC) bases mightdestroy bombers at or near their bases. Second, air defensesmight try to inflict significant attrition on aircraft before theycould use their weapons.

Prelaunch Vulnerability

There is no doubt that most bombers not on alert at the timeof an SLBM or ICBM attack on their bases could be destroyed.Although only 30 percent of the U.S. B-52 force is maintained onground alert under normal peacetime conditions, in time of crisiscrews could be recalled to their bases and the vast majority ofthe force placed on alert. A surprise attack on non-alert bombersi s often used, however, as a conservative assumption in assessing

bomber survivability.Bombers on alert would be more difficult targets, but many

observers believe there is reason for concern about the surviva-bility of this portion of the force as well. These observersbelieve that it might be possible for Soviet submarines to firetheir missiles from positions close to U.S. shores, therebydestroying a large part of the alert bombers at or near theirbases. Although the survivability of alert bombers is a v e r yimportant concern, there are several reasons to question thisscenario.

Most importantly, planning a coordinated attack on .S.bomber bases would present an adversary with difficult, perhapsinsurmountable, problems. First, in order to minimize missileflight time, and th us warning time, Soviet submarines would haveto station themselves close to U.S. coasts. Such a move wouldprobably be detected by U.S. antisubmarine warfare (ASW) sensors,thus providing the United States with warning of an attack. Sincedetection of provocative Soviet submarine deployments would enable

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the United States to put the entire bomber force on alert, anattempt to launch a surprise attack on alert bombers could be acounterproductive tactic. Furthermore, since a damage-limitingstrike would probably be considered by the Soviet Union only in atime of extreme crisis, U.S. forces would almost certainly be in ahigh state of readiness at the time of an attack.

Even if U.S. bombers w ere not in their highest state ofreadiness, and even if Soviet submarines could position themselvesfor attack without being detected, there are reasons to doubt thatalert aircraft could be destroyed at their bases. Given a bomberreaction time of about three to six minutes, 19/ alert aircraftwould have more than enough time to escape attacks on theirbases by SLBMs with flight times of ten to fifteen minutes. 2Q/Missiles flying on fast, depressed trajectories would take aboutseven minutes to reach bomber bases, 21/ providing a slim marginof safety for alert bombers. There is no evidence, however,that the Soviets have tested SLBMs flown on depressed trajec-tories. 22/ If such tests were to be carried out at some futuredate, there would be greater cause for concern about the prelaunchsurvivability of alert bombers, and several corrective measuresto insure the survivability of the bomber force might be calledfor. These measures include the dispersal of bombers to a largernumber of bases in the interior of the continental United Statesand the maintenance of higher alert rates and a more rapid re-action status for alert aircraft.

19/ See Alton H. Quanbeck and Archie L. Wood, Modernizingthe Strategic Bomber Force (The Brookings Institution,1976), pp. 46-47; and Francis P. Hoeber, Slow to Take Of-fense: Bombers, Cruise Missiles, and Prudent Deterrence(Center for Strategic and International Studies, GeorgetownUniversity, February 1977), pp. 84-85.

20/ Statement of James R. Schlesinger in Briefing on CounterforceAttacks, Hearings before the Subcommittee on Arms Control,International Organizations and Security Agreements of theSenate Committee on Foreign Relations, 94:1 (September 11,1974), p. 22.

.?1/ Quanbeck and Wood, op. cit., p. 44.

22/ Donald H. Rumsfeld, Annual Defense Department Report, FiscalYear 1978, p. 123.

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Penetration Survivability

Even after bombers have successfully escaped attacks ontheir bases, they still face threats to their ability to carry outtheir retaliatory mission. The Soviet Union has deployed anextensive network of air defenses consisting of about 6,500surveillance radars, 2,540 interceptors, and 10,000 surface-to-airmissile (SAM) launchers. Z3/ Furthermore, it is projected thatthese defenses will be further strengthened with the eventualdevelopment of an advanced Soviet air defense system againstlow-flying aircraft.

There would be several ways to degrade these defenses ina nuclear war between the United States and the Soviet Union.First, surviving U.S. land- and submarine-based missiles might beused to destroy a large portion of Soviet air defenses before thearrival of the bomber force. 24/ Second, surviving air defensescould be attacked by the nuclear-armed Short Range Attack Missiles(SRAMs) carried by penetrating bombers. Furthermore, even withoutthese potent nuclear countermeasures, the record of U.S. elec-tronic countermeasures (ECM) used by Americans in Vietnam andIsraelis in the 1973 Middle East war indicates that these measurescan be extremely effective against Soviet air defense systems. 25/Finally, in the future the U.S. bomber force will include thous-ands of long-range cruise missiles whose low-level flight andsmall size will help them avoid detection and whose large numbersshould be capable of saturating surviving Soviet defenses.

THE SUBMARINE-BASED FORCE

Ballistic missile-launching nuclear-powered submarines(SSBNs) comprise the third element of the U.S. strategic T R I A D .

Because these submarines carry about half of the warheads in theU.S arsenal a measure of the ability to attack large numbers oftargets their destruction w o u l d be an especially importantrequirement for a successful Soviet damage-limiting s t r ike.

23/ Ibid. p. 58.

24/ See James R. Schlesinger, Annual Defense Department Report,FY 1976 and FY 197T, p. 11-20.

Quanbeck and Wood (op. cit.) cite estimates of 3 percentU.S. attriti on in the 1972 bombing raids against NorthVietnam and 1 to 1.5 percent Israeli attrition in the 1973war. See pp. 64-65.

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At the present time, U.S. nuclear-powered submarines atsea are considered essentially invulnerable to Soviet attack.This belief is based on several factors. First, U.S. submarinesare considered to be extremely quiet, providing little, if any,chance for Soviet acoustic sensors to detect them in the openocean. Second, Soviet antisubmarine warfare capabilities are notconsidered particularly sophisticated. Finally, geography is adistinct disadvantage for the Soviets because they have verylimited access to the open oceans where most U.S. submarines areexpected to operate.

Not only is it likely that current U.S. strategic submarineswill remain highly survivable into the foreseeable future, butTrident submarines now under construction will be even quieterthan current submarines and will be equipped with the most soph-isticated passive sonar equipment available. In fact, Navyofficials have stated that the combination of quieting improve-ments and advanced sonar equipment will allow Trident submarinesto detect enemy forces before they are themselves detected. 26/As a result, Soviet antisubmarine warfare forces would have great

difficulty detecting and destroying U.S. submarines.The key to any effort to attack submarines at sea is large-

area ocean surveillance. The Soviets have no such system today.To hedge against th e development of such a system, possiblysatellite-based, the 4,000 nm. range of the new Trident I missileplanned for deployment on Trident submarines as well as tenPoseidon boats will dramatically expand the ocean area availablefor on-station patrol. Moreover, the large Trident submarinetubes allow for the possibility of a 6,000 nm. range Trident IImissile. Such an expansion of patrol area greatly magnifies thetasks faced by an enemy seeking to track and destroy a largenumber of submarines that are trying to avoid detection.

Trident I will not only double the range of the olderPoseidon missile, but reportedly it will also increase the des-tructive power carried by each missile from an average of ten40-kiloton warheads to eight 100-kiloton warheads (see Table 2).It has also been reported that the Trident II missile, if de-

26/ Depar tmen t of Defense Autho riz ation, Fiscal Year 1977,Hearings before the Senate Armed Services Commi11ee, 94:2(1976), Part 12, pp. 6548-49.

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ployed, could carry 14 150-kiloton warheads or seven MK-12A350-kiloton warheads. 27/

One area of potential submarine vulnerability that doesconcern the Navy involves the methods used to receive communica-tions. At the present time, submarines use an antenna closeto or above the surface of the ocean for this purpose. As aresult, a Soviet satellite system that could detect these antennasmight pose a threat to the survivability of all or part of thesubmarine force. For this reason, the Navy has proposed con-struction of an Extremely Low Frequency (ELF) communicationssystem, called Seafarer, that would allow receipt of messageswithout the necessity of bringing either the submarine or itsantenna close to the surface where it is most vulnerable. There-fore, if a threat to submarine concealment should develop, seriousconsideration should be given to construction of an ELF-likecommunication system.

While submarines at sea are now very survivable and willlikely remain so into the foreseeable future, submarines inport remain highly vulnerable. The Trident submarine offersthe promise of future improvement in this area as well. About 55percent of the Polaris and Poseidon submarine force is maintainedat sea during peacetime. 2 8 / Although Defense Department offi-cials have stated that this percentage can be raised to almost 99percent of submarines not in overhaul during a crisis, 29/ orabout 80 percent of the total submarine force, this leaves a largepart of the U.S. sea-based deterrent vulnerable to a surpriseattack. With such advances as a longer life reactor core andimproved logistics facilities, however, Trident submarines areexpected to maintain a peacetime at-sea rate of 66 percent. 30/This represents an increase in potential survivability of 20percent and is equivalent to the deployment of additional sub-marines and missiles.

2 T / See "New Propellant Evaluated for Trident Second Stage,Aviation Week and Space Technology, October 13, 1975, p.16-17.

28/ Senate Armed Services Committee, Department of DefenseAuthorization, Fiscal Year 1978, Part 10, p. 6621.

29/ Ibid., p. 6624.

30/ Ibid., p. 6621.

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In sum/ the U.S. submarine force, which carries approximatelyhalf of all the warheads in the U.S. strategic nuclear arsenal,appears to be the most survivable part of the TRIAD. Programs nowunderway or options available in the future should maintain thissurvivability into the foreseeable future.

THE VULNERABILITY OF THE TRIAD

Although it is useful to examine the vulnerability of thethree elements of the strategic TRIAD individually, it is the sizeof all surviving U.S. forces that determines whether a dangerousvulnerability to a Soviet first strike exists. It is likely thatan adversary interested in a counterforce strike against theUnited States would attack all three forces together. To dootherwise would only increase the damage that surviving Americanforces could inflict in a nuclear war.

To attack all three elements of the U.S. strategic TRIADtogether, however, would introduce new complications for the

attacker, since each part might contribute to the survivability ofanother. For example, simultaneous attacks on bomber bases andICBM fields might provide the irrefutable evidence of nuclear warnecessary for a decision to launch ICBMs on warning, a possibilitythat would have to give a potential attacker cause for concern.Furthermore, detection of preparations for an attack, such as thepositioning of a large number of missile-carrying submarines closeto American shores or unusual activity in enemy ICBM fields, mightallow the United States to put a much larger percentage of its ownforces on peak alert, thereby increasing their survivability.Because of these interactions, certain ambitious enemy attacks,such as a surprise attack on alert bombers, would probably beespecially risky undertakings.

U.S. Vulnerability in the Mid-1980s

The worst case faced by the United States through the early1980s would be a comprehensive surprise attack on U.S. nuclearforces in their day-to-day alert posture. Although it is diffi-cult to find a motive for an unprovoked surprise attack, thisscenario does provide a lower bound for the number of U.S. sur-viving forces. In such an attack, Soviet submarine-launchedmissiles would be targeted against U.S. bomber bases, and 70percent of the B-52 force would be destroyed. Attacks on U.S.submarine ports would be expected to destroy the 45 percent of thePoseidon fleet and the 34 percent of the Trident force not at sea.The U.S. ICBM force would come under attack by some 260 SS-18

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missiles, each carrying eight 1.5 megaton warheads accurate toperhaps 1,200 feet. After such a surprise attack, the UnitedStates would probably be left with about 6,400 warheads and 1,800

equivalent megatons. (The Soviets would have a reserve forceconsisting of about 6,000 warheads and 6,000 equivalent megatons.)

Since 1,000 Poseidon SLBM warheads could destroy about75 percent of the Soviet industrial targets (Trident warheads willbe even more destructive), and since the same number of cruisemissiles could destroy over 80 percent of the Soviet industrialbase, the United States would have more than enough weapons inboth the bomber and submarine parts of the TRIAD to destroy theSoviet Union as a modern industrial society. 31/ Thus, given thesurvivability of at-sea submarines and alert bombers, a Sovietcounterforce attack on U.S. ICBM silos, submarine ports, andbomber bases does not offer the prospect of successful damage-limiting. In addition, since the United States would have moreweapons than those required for attacks on Soviet cities, otherU.S. retaliatory options, such as attacks on Soviet militarytargets, would be available after a Soviet first strike. More-over, the United States could maintain its nuclear force over anextended period of t ime; , since most of the surviving U.S. weaponswould be in submarines, which can remain at sea and effective forweeks or months.

If it is assumed that a nuclear war would not start with atotally unprovoked surprise attack, but rather after a periodof rising tensions, then U.S. forces would be in a high state of

readiness, often referred to as a generated alert posture, at thetime of the attack. In this case at least 80 percent of thebomber force 32/ and 75 to 85 percent of the submarine-basedforce 33/ would s u r v i v e ; a counterforce attack, leaving the UnitedStates with significantly more warheads and equivalent megatonsthan in the surprise attack scenario. An attack on U.S. forces ina generated alert posture would leave the United States with a

31/ For an examination of the retaliatory damage that U.S. forcescould do, see the forthcoming companion paper on retaliatoryissues.

32/ Military Posture and H.R. 11500, Hearings before the HouseArmed Services Committee, 94:2 (1976), Part 5 , p. 264.

33/ Senate Armed Services Committee, Department of DefenseAuthorization, Fiscal Year 1978, Part 10, p. 6621.

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substantial force of over 10,000 warheads and 3,000 equivalentmegatons.

U.S. Vulnerability in the Mid-to-Late 1980s

By the mid-to-late 1980s, the vulnerability of U.S. strategicforces may grow. In particular, if the Soviets develop and deployan ICBM accurate to about 600 fee t , , the survivability of theMinuteman force could be seriously threatened. The shrinkage ofthe submarine force with the block retirement of the Poseidonfleet during this same period will also reduce the number ofsubmarine-based missiles, although the increased payload andat-sea availability of the Trident force will somewhat offset thistrend. If the Soviets were to attack U.S. forces in their day-to-day alert posture, and if about 90 percent of the ICBM force weredestroyed, the United States would still have over 4,500 warheadsand 1,400 equivalent megatons.

In the more likely case of a U.S. generated alert posture,the United States would have over 8,000 warheads and 2,700 equiv-alent megatons. The expected results of these Soviet counter-force strikes are summarized in Table 3. _34/

All the results presented above are expected value resultsbased on specific assumptions about he operational performance ofweapon systems in terms of accuracy, reliability, warhead yield,silo hardness, and the ability to avoid fratric ide. Becausea great deal of uncertainty surrounds estimates of these par-ameters, the Soviet leadership would have to consider the rangeof reasonable attack outcomes as well as point estimates. Givenlarge variations in the number of U.S. ICBMs that would survive aSoviet attack against them, a counterforce strike would entail

great risks. 35/

34/ Results for 1990 assume an ICBM force without the addition ofMX or MK-12A warheads on Minuteman III missiles, an SIBMforce based in five Poseidon submarines and 20 Trident boats(but without Trident II missiles), and a bomber force iden-tical to that of the middle 1980s (see Table 2, secondpart).

35/ For details on atta