PROBABLE SOVIET POSITION ON NUCLEAR WEAPONS TESTING ( SNIE 11-9-59)

Created: 9/8/1959

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SNIE9

SPECIAL

NATIONAL INTELLIGENCE ESTIMATE NUMBER

PROBABLE SOVIET POSITION ON NUCLEAR WEAPONS TESTING

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Intelligsnce

PROBABLE SOVIET POSITION ON NUCLEAR WEAPONS TESTING'

THE PROBLEM

To assess the relative weight of weapons requirements and other considerations in determining the Soviet position on further nuclear testing, and to-estimate the Soviet attitudes toward complete discontinuance of nuclear weapons testing and toward limited discontinuance.1

THE ESTIMATE

Broadly speaking, the considerations which lie behind the Soviet position on furthertesting are of three kinds: technical, stralegic, and political. Technical considera-Uons have to do with the stage of research and development in which the Soviets find themselves with respect to nuclear weapons-how urgent do they consider the necessity of further testing In order to round out their arsenal of nuclear weapons, to improve the economy or efficiency of those they have, or to realize thc potential of new devices? Strategic considerations relate to the effect of further testing on the world balance offar do the Soviets believe they would derive advantage or disadvantage in this respect fromesumptioniscontinuance of nuclear testing? PollUcal considerations have to do with the advantages which thc Soviets might see for themselves in

'See NIE ll-ft-SB. "The Soviet Attitude Towardftlcd8uller discussion of the arguments which arc summarized in lhc present paper.

1 Limited discontinuance would ban for anperiod any testing In thc atmosphere and outer space, on the earth's surface, andonly contained underground tests would be sanctioned.

a continuance of their strong propagandists stand against further testing, and with the longer-range benefits which they might hope for if an agreed discontinuance of nuclear testing could be established as the first step towards other agreements. We propose to discuss each of these considerations briefly, and lo estimate how the Soviets weigh them against each other in arriving at their

The Soviets now haveideof fission and thermonuclear weapon types. Their test series have shown that they could obtain yields ranging from less than three KT from fission devices to eight MT from thermonuclear devices. They thus canweapons suitable for tactical ground force use and naval employment as well aside range of aircraft and missilesystems This capability probablyefficient use of nuclear materials in air defense warheads. Significant improvements in stockpiled weapons arc certainly being madeirect result of the .tests completed In

An analysis of Soviet nuclear weaponsdocs indicate that there are several areas in which lhc USSR might desire to conduct

further tests. These areas include: (a) high altitude or space tests related to AICBMor proof tests; (b) tests of low-yield, light, tactical devices; (c) tests directedmaterially increasing fissionableeconomy; (d) tests of "Clean" devices; and (e) tests of thermonuclear weapons with yields above eight MT. In addition,of existing designs would be desirable in any test series.

Almost certainly there are pressures in the Soviet Union, on both technical and military grounds, for continued nuclear testing hi some or all of these fields. Over the long-run the Soviet nuclear weapon design andcapabilities could only be marginally Improved without further tests. However, the available spectrum of nuclear weapons is probably adequate to meet their basic military requirements. On balance, we believe that the Soviets currently estimate that thepotentialities for weapons Improvement would make further testing desirable, but do not provide an overriding requirement for the resumption of tests at this time.1

From the strategic point of view, thcprobably believeontinuation of nuclear testing by both sides would be unlikely to alter the relationship of military powerthe US and the USSR in any decisive way. In any case, they are almost certainly unable to estimate with confidenceontinuance of nuclear testing would operate to their advantage rather than to that of the US. They may believe that, despite certain US superiorities in weaponstabilization of nuclear weapons technology at present levels of development would serve Soviel military interests better thanontinuance of testing by both sides. On these grounds, therefore, we think that the Soviets almost certainly are willing, though not necesarily anxious, to have both sides cease testing.

olitical point of view, totalof nuclear weapons testing wouldajor step in the Soviet effort to

'For further discussion of the technical aspects see Uie Annex to this estimate.

single out nuclear weapons as different from and more repugnant than other weapons. It would crown with success the long public Soviet demandest bah and raise the prestige of the USSR. It would thus serve long-range strategic and political alms bya springboard for intensified agitation against further deployment of nuclearabroad, against initiating the use ofweapons in any situation, and evenomplete ban. Even though the Soviet leaders would probably see little prospect of involving the West in negotiations on these Issues and still less prospect ot gettingthey would calculate that by focusing renewed attention on them, they couldpolitical problems within the free world and inhibit Western defense activities. Any resulting relaxation of Western defenseany divisions within NATO and any progresslimate Inhibiting Western use of nuclear weapons would be viewed by the Soviets as important gains.

A total discontinuance of nuclear weapons testing would Inhibit other countries.Communist China, from persisting into develop their own nuclear weapons. The Soviets would welcome the fact that the problem created within the Westerny French desires toeaponsprogram would be intensified. While Communist China would probably press for acquisitionuclear capability, the Soviets presumably believe that they could meet this pressure by promising to provide appropriate nuclear support to China, and by arguing thatext step they would work toward the withdrawal of US nuclear weapons from Eurasia.'

In sum, then, we believe that the Soviets see no overriding current technicalfor continued nuclear weapons tests, and no assurance that they wouldtheir relative military position by such tests (assuming, of course, that tests wereby bothccordingly, we believe

'For furUier discussion of Chinese nuclear ca-pablllUes and Sino-Soviet nuclear arrangements, sec, "Communistaragraphsnd S3ateduly (Secret!

that the major factor now determining the Soviet position on further nuclear testing ls their evaluation of the political andgains to be expected from aof tests. We believe that In their opinion these gains would be considerable, and In the long run would contribute substantially to their strategic objective of weakening the US both militarily and politically, outweighing any immediate technical and militaryto be derivedesumption of testing.

follows from thc above conclusionSoviets wouldotaland would be coolimited one.they could calculateurface,and space test ban wouldthem to stigmatize nucleara degree, and thus to gain some of theof the completeimitedon nuclear testing whichtests would allow the USSRsome of the potentialities fordevelopment, though withand difficulty than underunrestricted testing. (Such anof course, also permit the US andimprove their weapons, and in limeother nations to develop nuclearWhile it is therefore possible thatwould agreeimitedwithifupture inhighly unlikely. The chances arethey would settleimitedwithout international controls.

believe it most probable that thecontinue to pressotalof nuclear weapons tests,the approval which this course ofin many parts of the world.moreover, that the Soviets will agreetotal ban on weapons tests, withcontrols, provided that they succeed ininspection monitoring to what theyan acceptable limit in terms of theirrequirements for state security.such an agreement they will continue

their propaganda against tests. We do not believe that, for the time being, the Soviets will resume testing (in the ^absence of an agreed ban) unless and until the US does so; in effect, therefore, they would have amoratorium without controls.

ith the alternatives open to them, we believe that the Soviets would prefer not to risk entering into an internationallyagreement with the prior Intention to evade it by illicit weapons tests. If they regarded the need for testing as so great, they would instead probably defer anor agree to aIfchanged subsequent "to anso that they believed that significant gains could be realized from renewed testing, they would have to weigh these potential gains against the likelihood and consequences of detection. It Is unlikely that the Soviets would risk what they regarded as anchance of detection and disclosure of illicit tests. However, if they came to believe that an overriding necessity for testing had arisen, they would probably renew testing, employing some gambit such asestern power of breaking the agreement, seeking to justify their renewed testingetaliatory action to meet new and legitimate defensive requirements. If Communist China were not covered by the agreement, themight resort to testing on Chineseterritory.

onsiderable period elapses without an agreed nuclear test ban. the willingness of thc Soviets to forego testing may change. The evolution of military requirements for new advanced weapons systems, or thepossibilityechnical breakthrough in the laboratories, might create in the USSR much stronger pressures for resumption of tests than we believe now exist there. These pressures could persuade thc Soviet leaders that an agreed test ban was no longer to the advantage of the USSR, or possiblyimited discontinuance of tests, ratherotal ban. was desirable.

ANNEX

SOVIET TECHNICAL MOTIVATIONS TO RESUME NUCLEAR

WEAPONS TESTING

SUMMARY

the completion of8 test series, the Soviels have available to wideof fission and thermonuclear weapons which are probably adequate to meet their basic military requirements. This spectrum includes devices suitable for ground force and naval employment as well aside range of aircraft and missile delivery systems. This capability also probably includes efficient air defense warheads and thermonuclearyieldingTT.

Based upon the nuclear weaponand test capabilities evidenced by the Soviets to date, we estimate that with resumed unlimited testing they could increase their thermonuclear yields, improve yietd-to-weight ratios and economy of fissionable materials in their weapons, and overcome any lack of knowledge of high altitude effects. They could also develop new weapons to satisfy future military requirements for advanced weapons systems.

Under an atmospheric and outer space lest ban, the Soviets are capableajoreffort but the .advances would be somewhat slower and they would be unable to close any gap that might exist between the US and Soviet knowledge of high altitude effects. We have no evidence that the Soviets have conducted deep underground nuclear tests, and wc estimate that they have not done so. However, the conduct of such tests tothe collection of adequate diagnostic information Is fully within their technical capabilities.

If no further nuclear testing occurs, their over-all nuclear weapon developmentcould only be marginally improved.

Thc Soviets are technically capable ofclandestine underground testsomplete nuclear test ban and at presentnique missile capability for clandestine nuclear test attempts in outer space. Some significant design progress could be achieved if several limited test series were conducted, particularly in very low-yield weapons and in over-all fissionable material economy.

An analysis of Soviet nuclear weaponsindicates that there are several areas in which reasonably adequate tests may not have been conducted to date and which probably create technical pressures within the USSR for thc resumption of nuclear tests. These(a) high altitude or space tests related to AICBM effects or proof tests; <b> tests of low-yield, light, tactical devices; (c) teststoward materially increasingmaterial economy; (d) tests of "clean" devices; and (e) tests of thermonuclear weapons with yields above eight MT. Wethat at present these areas do notcither individually or collectively, an overriding technical motivation to resumeOn the other hand, the evolution ofrequirements for new advanced weapons systemsossible technical breakthrough in the nuclear weapons laboratories could create in any or all of these technical areas much stronger pressures for the resumption of nuclear tests.

of nuclear testing by theintensify technical motivations forlo resume testing.

DISCUSSION

INTRODUCTION

n assessment of Soviet technicalto resume nuclear testing, whether orest cessation agreement ls negotiated, must consider the present state of Soviet weapon art, current and future Soviet(or improvement in their nuclear weapons, and likely Soviet assessment of the technical capabilities of existing and proposed test detection and identification systems. Soviet capabilities for undetected evasionest ban will be considered in this discussion in light of two assumptions: first, that only contained subsurface tests willhose in which no venting Into theoccurs; and second,omplete test ban with the necessary inspectionwill be in effect.

METHODS OF EVADING DETECTION

he effectiveness of all the detectiongiven above are dependent upon Soviet knowledge of and ability to employ themeans of decreasing the likelihood of detection. These means include such possible techniques as decoupling of subsurfaceto reduce the seismic signal produced.

'DecoupUngest technique for underground explosions which Is designed to reduce the amount of energy going into Uie seismic signal. Decoupling may theoretically be accomplished by delonaUne the deviceargecavity or hole, the dimensions and shape of which are dependent upon theyield.

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of space detonations to reduce thc radiations emitted by the nuclear explosion, and positioning the explosion either atlarge distances in outer space orplanetary bodies for concealment. Such techniques have been made known to the Soviets, and It is within their capability to exploit them.

of the methods above will Increaseand expenditure required fordecrease the amount, or at leastthe attainment, of diagnosticdesired from each test.should the Soviets choose to riskand exposure, technical informationgained by testing under thesefurther progress in nucleardevelopment.

PRESENT STATE OF SOVIET NUCLEAR WEAPON DEVELOPMENT

the preparation of SNIEand Likelihood of Soviet EvasionNuclear Testhe Soviets have conducted twoseries of nuclear tests. These seriesa total ofests which7 and 3

SOVIET REQUIREMENTS FOR FUTURE TESTS

Future Soviet requirements for nuclear tests are dependent upon militaryon which adequate Intelligence does not exist. However, the characteristics of the varied nuclear test devices that have been detected clearly Indicate that the Sovietplannerside spectrum of modem nuclear weapon designs available to them for all of the weapons systems we estimate that they possess. Furthermore, we estimate that there Is virtually no major principle of weapon design which thc US exclusively holds.members of the Soviet Delegation to the current Geneva Conference on thcof Nuclear Weapons Tests haveInformally that there is militarywithin the USSR for the resumption of nuclear tests.

There are five discernible areas wherein adequate tests may not have been conducted to date which must be evaluated bothand singly:

l. Tests related ta AlCBM effects orat altitudes well above thethann space.

^Ja large volume of information has been published on US high altitude tests, which may reduce Soviel requirements for high altitude effects data.

b. Tesfs o/ lout-yield, light, tactical

J However, we believe that they seriously lag behind US capabilities, particularly In fractional KT weapons.

c. Tests directed toward materiallythe economy of fissile materials, particularly in the larger TN devices. Soviet nuclear weapons in the higher yield ranges consume large amounts ofmaterials, and it Is well within Soviet

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capability to achieve substantial economies by further testing.

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dditional tests will be required if the Soviets desire clean weapons in any yield range.

weapons witheight MT. P

Any requirement for such very high-yield devices would probablytesting inT yield range.

addition, thc refinement of existingshould be includedesirablein any test series.

POSSIBLE TEST PROGRAMS

I presents our estimate ofpotentialities for nuclearunder three conditions:nlimited testing;artialandomplete test ban.cost estimates are impracticableof the scant knowledge available onof evasion techniques, thus weattempted to indicate relative

POSSIBLE GAINS WITHOUT TESTING

should not conclude that theweapons program will beno tests are conducted. Significantin stockpiled weapons arebeing madeirect result of thecompleteduturestudies of nuclear materials inenvironments and in amountstoignificantcan also contribute to someof the weapon art, particularlylow-yield devices. Improvement inhardware and techniques canthe military effectiveness of theSoviet nuclear stockpile. Redesigntheoretical studies may be made to abut wc believe the Soviets would hesi-

tate to stockpile new designs without proof-testing them. Successful espionage against the West might permit Isolated advances In the Soviet program

TECHNICAL MOTIVATIONS TO RESUME TESTING

We believe that the five areas requiring further tests, as listed Inreate technical pressures within the USSR for the resumption of nuclear tests. However, we do not believe these areas currently provide an overriding technical motivation touclear test ban thc Soviets will continue to pursue thc development of improved weapons systems and the study of improved nuclear weapons technology.eriodew yearn the evolution of military requirements for new advanced weaponsand improved nuclear devices could create in any or all of these technical areas much stronger pressures for the resumption of nuclear tests.

There isossibility that as aof laboratory research which is beyond our capacity to predict, the Soviets mayechnical breakthrough leadingajor Improvement In nuclear weapons design This possibility appears remote; however, should it occur, it could produce with the passage ofery strong technicalfor tlie Soviets to resume testing.

Resumption of nuclear testing by the US would Intensify technical motivations for the Soviets to resume testing.

If the US resumes underground nuclear tests for the specific purpose of acquiring further technical Information on seismic effects pertinent to the controlomplete test ban, this probably will also promotewithin the Soviet Union forof testing. However, the Soviets would probably refrain from testing until they have made capital of any potential propagandaIf the Soviets, in time, conduct similar tests, wc believe they would certainly exploit them for weapons development

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