Created: 4/25/1961

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The following intelligence organisations participated In the

hSuit he Deportment, o. State, the Army, the Navy, the Atr Force. The Joint Stag ana the Atomic energy Commission

Concurred In by the UNITED STATES INTELLIGEXCE BOARD onApnl mt Concurring were The Director ofand Research. Department of State, the Assistant Chief of Stag tor Intelligence. Department af the Army;ant ChiefOperations UntcUigencei. Deportment of the Mesm; the Assistant Chle, of Stag.VSAF lhe Dueeto, for Intelligence. Joint Slag, the Atomic Energy LommlHkM ftepresentathe to the USIB; the Assistant t0 the Secretary of Defense. Special Operations, and the Director of lhe National Security Agency The Assistant Director fed.Bureau of Inxiestigatum. abstained, the subject being out. side of hu |unsdictlon.



estimate was disseminated by the Central Intelligence Agency. Thisfor the information and use of tho recipient, and ot persons under his Jurisdictionneed to know basis. Additional essential dissemination may be authorized byofficials within their respective departments.

of Intelligence and Research, for the Department of State

Chief of Staff for Intelligence, Department of the Army

Chief of Naval Operationsor the DepartmentNavy

of Intelligence. USAF, for the Department of the Air Force

for Intelligence, Joint Staff, for The Joint Staff

of Intelligence, AEC, for the Atomic Energy Commission

Director, FBI, for thc Federal Bureau of Investigation

to the Secretary of Defense, Special Operations, for theDefense

of NSA for the National Security Agency

j. Assistant Director for Central Reference. CIA, for any other Department or Agency

This copy may be retained, or destroyed by burning in accordance with applicable security regulations, or returned to the Central Intelligence Agency by arrangement with the OITlcc of Central Reference, CIA.

When an estimate Is disseminated overseas, the overseas recipients may retain Iteriod not In excess of one year. At the end of this period, the estimate should cither be destroyed, returned to the forwarding agency, or permission should be requested of the forwarding agency to retain it In accordance with2

" l' ill Hi Ij hum fhi Ii iiti. ilimiliUiLi nluiuifiql

WARNINGlft! contains Information_jgceTTr.fl therrfftei; state* withinrTceiplonage laws,ie trans-mLorion or^amlaUon of wractr^RBtaunanner lo anjieEauthorlzed personrohibit


NaUonal Security Council Department of State Department of Defense Atomic Er.ergy Com ml Ml on Federal Bureau of Investigation



To estimate whether the Soviets have conducted clandestine nuclear teststhe moratorium which began in


USSRuclearnd sincehas indicated that it. along with thelhc UK. wasoratoriumIn considering whether or notclandestine nuclear tests duringthe Soviet leaders would haveweigh the Importance of obtainingdala for their nuclear weaponspossibility of being caught, and thcexposure.

Considerations Affecting the Soviet Position

Motivations. Sovietdevelopment activity has continuedhigh level during the moratorium.wc believe that only limitedin Soviet weapons capabilitiesbeen possible without further tests.of Soviet weapons developmentthe following principal areas inUSSR inight have desired lo conducttests sincea) teststo antiballistic missile effects;ow yield, light weight devices;oward increasing economy Of(d) tests to improve theratio of all classes of nuclearnew areas of development, such asenhanced radiation and pure fusion weap-

ons of low yield. Of these, the Sovietwith regard to antiballistic missileprobably is the most urgent.

he necessity for additional Soviet tests to optimize or improve existing weapons, or to develop new designs, depends heavily on Soviet strategy and on thc character or future weapon systems. We believe that nuclear weapons arc available for all the deliverywhich we know lo be in the Soviet arsenal or which we estimate to have been underHowever, many of these weapons probably are noi of optimum design, andgaps in lhe Soviet knowledge on weapons effects for certain military applications may exist. Almost certainly there have benwithin the USSR for continued nuclear testing, on all the various grounds cited above

Political ConsideraUons. The Sovietmust have recognized that il wouldajor blow to their public posilion if it were demonstrated to the satisfaction of the bulk of lhc Free World nations that they had been testing nuclear weapons covertly They have .set great store by their campaign to capture the "peace" theme in world opinion and to present themselves as thc proponents, and the West as lhe opponents,alt to the arms race. In balancing the possible political costs against the considerations arguing for covert


wc believe that the Soviet leaders would have required very high assurances that such testing could not be proved, or evencharged, against them before entering onrogram.inimum, thiswould have narrowed the choice of tests they might make;aximum, it would have Inhibited them from testing at all.'

the past year or so, some UShave raised In the Soviet mind thethat the American side mightresume testing. This factorincreased weight to argumentsUSSR that It should not run thc riskcaught testing during this period.

Techniqwes Minimiiing the Risk of Detection

if the Soviets attempted to conductnuclear tests, they would have sought to minimize the risk of detection by doing so under conditions which did not put nuclear debris Into theny such tests would have had to be conducted eitheror in space. The possibility that tests in space can be detected decreases as thefrom the earth Is increased. Tests in either of theseor outerwithin Soviet capabilities.

At present, the US detection system has no capability to detect nuclear explosionsIn outer space. However, intelligence doesapability to direct attention to those missile/space activities which could be employed in such testing, intelligence prob-

1 The Assistant Chief of SUff. Intelligence. USAF. belleTCi Uiat UiU paragraph overemphasises the Soviel concernavorable international image

Further, there i* Utile likelihood of the expoiure problem arisingthe SovieU can use, Indeed probably have uaed, testing techniques that deny connimai&Sn of violations.

' Pure fusion devices wUl not produce fin ionand therefore will not produce evidencetesting We have no knowledge of Sovietpment In this Held, and Uie feasibility of suchconcepts hut not yet been conclusivelyThe Auutant Chlel of Staff.USAF. eoniWeia Uiatvidence in-dlcalea Uiat the Sorieta haverfclne on the development, ol pure fusion weapons since at

ably cannot establish whether nuclear tests in space have in fact taken place, although it might provide some basis for judgment.

ully contained underground tests, like space tests, provide no airborne radioactive debris which would provideuclear event. However, there are limits to the yields of devices (up toT) which can feasibly be tested in thisalthough many of thc principal areas of development In which the USSR might have desired to conduct tests since8 {as Indicated ln paragraphbove) could have been accomplished by underground testsew kilotons. Moreover, the signalsby such tests may be detectable by seismic means, although such detected signals cannoi be distinguished from natural seismic events. The capability of the seismicof the US detection system can bedegraded by conducting the lestard medium, such as granite or salt, or by decoupling. An even greater reduction could be achievedombination ofard medium. However, the scale of operations required for carrying out decoupling tests Is such lhal other intelligence techniques would have, ar-Increased opportunity for detecting them

Evidence of Possible Testing

roof that nuclear weapons tests haveis difficult to obtain without collection of debris, since the other indicators of testing activity are susceptible to alternativeConversely, proof that tests have not occurred has not been possible.. the US has collected no nuclear debris or other conclusive evidence that the SovieU have conducted nuclear tests. Eacharge number of seismic events areIn thc USSR; some of those occurring during the moratorium could have been thc result of nuclear explosions, but none could be identified as such. There are indications from other intelligence sources which have raised the possibility of Soviet evasion of the moratorium by means of containedtesting, but these also are susceptible to alternative explanations. Each suspected



or plausible Indication, must beseparately and exhaustively.

ccordingly, we have made an Intensive survey of all the evidence, from all sources and all regions of the USSR, bearing upon possible Soviet nuclear testing during the moratorium. Thc most suspicious evidence relates toTurkestan, ln particular around Osh. and to Scmtpalatinsk. The data are mostwith the thesis that the Soviets had conducted one or more large HE explosions near Osh in the winterart of their seismic improvement program or to study' methods of clandestine nuclear testing, bul the conduct of an actual nuclear testbe ruled out. Nuclear testing ln other areas in Southern Turkestan appears less likely than In the case of the Oshhe Semlpalatinsk proving ground area hasactive since the moratorium, andin0 shows evidence ofbut not recent low-yield, venting tests since the previous coverage invaluation of all evidence indicates It Is more likely that these tests occurred7 and the commencement of the moratorium in8 rather than during theperiod. An apparent ground zero area outside the fenced shot area wasul It Is probable lhat this ground zero has not yet been used. There is even less evidence relating to possible testing ui areas outside of Southern Turkestan and ScmipalatinsK.'

n technical grounds, we cannot exclude thc possibility lhat tests In containedenvironments or, less likely, very low-yield, vented explosions have occurredthe political costs of exposure havebeen regarded by the Soviets as high enough to deter them from any kind of nu-

'The Assistant Chief of Staff, Intelligence, USAF. believes that the evidence relating to Southernand the SemipalaUnsk area closelyattern ot activity indicative of nuclear testing and that this testing probably took place since

clear testing which had an appreciable chance of being detected, and wc doubt that theadvantages lo be gained from very low-yield tests would have been sufficiently great tn the Soviets' mind to Justify theirthem. The conclusion that the Soviets have conducted nuclear testsannot be drawn from the available

'The Atomic Energy Commission RepresenuUvc to the USIB. although concurringonclusion as to whether or not tne Soviets have beenclandestine tests cannot be drawn from the available evidence, considers that the techn leal advantages to be gained from very low-yield tests could have been suRlclenUy great In tho Soviets' mind lo jusufy their conducting them. He alsothat very low-yield tests conductedwould almost certainly not be detected.

'The Assistant Chief of Staff for Intelligence.ot the Army; the Assistant Chief of StafT. Intelligence, USAF; the Director for Intelligence. Joint Staff; and the Assistant to the Secretary of Defense, Special Operations, do not support thereached in this paragraph. They would substitute the following:

Thcuch that we cannot conclusively establish that the Soviets have or have not tested The USSR has considerable knowledge of ourdetecUon capabiliUes. Because of thisandigh degree of conventionalcould be maintained, the SovieU are no doubt aware that but negligible risk ot detection Iswith low-yield contained underground, or very low-yield atmospheric tests. Many of thedevelopment objecUvc* for which the USSR might have desired U> conduct testsould have been accomplished bytestsew kUotons. In particular, wc believe that thc need by the USSR for data on anti-ballistic missile warhead effects has been ertUcal In the period sincehis need could have been at least partially satlsAed by low-yield contained underground testing. In addlUon. wethat ihc potential of the all-fusion weapon theory, of which the Sovirtk are aware, ha*or will generate strong need for the very low-yield teau required for research and development and proof testing of all-fusion weapons. In the light of the evidence, thetr technical Deed lo have tested during the period sinceOS. coupled wtih the negligible risks Involved,trong possibility exists that Uiehave tested8

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