Created: 6/13/1968

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national intelligence estimate


The Clandestine Introduction of Weapons of Mass Destruction into the US

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The following inletliganee otganhation% patlicipatod in ihe preporolion of this eifinioie:

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Vice Adfn Rutui Tortar. Deputy DJec'oi. Ccntial

Air.ughe*.Drccor a' InleBigwa and Be forth.ol Stall

It. Gen. Jowph f. Carroll, ifca Dlieelor, Dnferne Intelligence

U. Can. Mar the II S. Cnrltf.adot. Notional Security Agency

Or.or the Awitcrt Caoorol Monogar, Atorak Energy Co*



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the clandestine introduction of weapons of massinto the us

the problem

To assess the capabilities of foreign nations to introduce biological, chemical, op nuclear weapons clandestinely into (lie US. and to estimate Ihe likelihood of such introduction over the next few years.


A. Virtually any industrial nation could produce biological warfare (BW) and chemical warfare (CW) agents and introduce theminto the US in relatively small quantities. We do not believe, however, that any potential enemy would plan the clandestine use of BW or CWcale sufficient to achieve strategic militaryWe do not rule oul die use of BW or CW for sabotage and other special purposes for which they could be very effective. The relatively small quantities required for these purposes could be covertly produced in the US without great difficulty or risk of detection. Therefore we consider thai their clandestine introduction would be unnecessary, and unlikely in view of ihe risks involved.

B. The Soviets could introduce nuclear weapons clandestinely into ihe US, and might considci doing so il iheyeliberate surprise attack on Ihe US. Considering the large numbers of stra-regie weapons now in (heii arsenal, however, the Sovicls would see the contributionlandestine emplacement effort as marginal and would consider any advantages it offered as outweighed by ihe risks of jeopardizing suiprise and ofS preemptive attack.


the Chinese liave no olher means of attacking thenuclear weapons, they mightlandestinewith (he object of deterring the US from attack onTheir capabilities to carry out such an effort, however,less than those of the USSR. Moreover, they could not bethe US would be deterred and they would have to considermight result in, rather than staveevastating USthese reasons, we think it unlikely that Communist Chinato introduce nuclear weapons clandestinely into the US.

have considered the possibilityhird countrymight assist the USSK or China in the clandestinenuclear weapons into the US. Wc consider this unlikely.that either the Soviets or the Chinese would seek to enlistof another nation inensitive undertaking. If theynation's leaders would almost certainly react unfavorably tothat could jeopardize: their national survival merely toor Chinese policy.



In coruidalng the clandestine inuoduction of weapons ol mass destroo tioti Into the US. enemy leaders would have to weigh any possible advantages against the grave consequences svhich svould follow from discovery. Despite all precautions there would always be risk of detection arising not only from specific US security measures, but also from the chance of US poneoation of the clandestine apparatus, the defection of an agent, or sheer accident. The enemy lenders would almost certainly judge that use of (his tactic would be regarded by tin* USarlike act, if notause for war. and that it would precipitate an international political crisis of the first magnitude.

We believe, therefore, that the tange ot circumstances in which weapons of mass destruction might be clandestinely introduced into theualean enemy nation would consider this course only in the coot at of planning an attack on the US or of deterring the US from an attack on Itself. Smaller stakes would not be worth the risk. Such weapons could not bo brought in secretly In sufficient quantities loecisive effect ou the outcomear. Any plans for their use, sve believe, would envision the use ol limited quantities to achieve results unattainable by other means.




irtually any industrial nation could produce biological warfare (BW> and chemical warfare (CW) agenli and Introduce them clandestinely into the US in relatively small quantities- Although small quantities of BW agents could be effective against large targets, the delayed action of such agents makes then unsuitable for use in situations requiring an immediate or precisely timed effect. Relatively large quantities of CW agents are required lo obtain effectiveover extensive target areas, ami it would be difficultntroduce them clandestinely in such quantities. Moreover, (he effects of BW and CW agents cannot always be predicted accurately, adverse weather can limit or even prevent the effective use of BW and CW agents against some targets.

We do not rule out the use of BW and CW for sabotage and other special purposes for which they could be very effective. But because the relatively small quantities required for these purposes could be covertly produced in the US without great difficulty or risk of detection, we consider that their clandestine introduction would be unnecessary, and therefore unlikely in view of (Ite risks involved. The following discussion, therefore, is limitedonsideration of the clandestine introduction ol nuclear weapons.

Only four foreignUSSR, the UK, France, and (Communistdeveloped and tested nuclear weapons Beyond these, only India is likely touclear weapons program in the neat several years; Israel and Sweden might do so. We can foresee no changes in the world situation so radical as to motivate the UK, France, or any of the potential nuclear powerso clandestinely introduce nuclear weapons into the US. For this reason, the balance of this discussion will benly with thenuclear powers, the Soviet Union arid Communist China.


G. Until the USSR and Communist China can produce nuclear weapons which could be adapted for clandestine introduction into the US. We estimate that the Sovietsroad spectrum of weaponsQ

Current Chinese weapons are probably fairly large and would piobably require more detailed assembly and chock out after being brought in ihan would Soviet designs.


/ Nudear weapons with wcighls of upounds could be brought across US borders by common means nl transport without grcaloviet weapon in this weight class couldield



a Chinese weapon couldThe difficulties and risks of intro-

ducing higher yield or heavier weapons into (he US. evenisassembled state, arc probably sufficiently great to seriously discourage soch atternpts. But higher yield weapons could be brought into US waters in merchant ships and detonated svithout removal from the ship. Such devices could also be carried in by foiling boats or similar small craft to which transfer had been made at sea.

Both the USSR and Communisl China could make the physical arrange* ments necessary to bring nuclear weapons secretly into the US, but Sovietin this respect are much greater than Chinese. We believe that if either country undertookrogram, they would rely on their own agent organizations rather than on political sympathisers in the US. Sovietservices haveigh priority to the development of espionage and sabotage capabilities in the US and presumably have formed an organization for the latter purpose- Should the Soviets undertake (he claodestiaeof nuclear weapons, they, almost certainly would employ the highly (rained and reliable agents of these services. They could also employ diplomaticand could bring in weapons or weapon components under diplomatic cover. The large diplomatic establishments in Canada and Mexico could serve as bases for the operation.

There arc no Chinese Communist diplomatic establishments in Ihe US, (Canada, or Mexico. The absence of such bases precludes the use of diplomatic pouches for the clandestine introduction of nuclear weapons or their components and the use of secure diplomatic communications for planning and control of such an operation; it also makes more difficult the introduction and control of agents. Nevertheless, the Chinese could introduce agents under the guise of bona fide immigrants.

considering Soviet and Chinese capabilities, wc have alsopossibilityhird countryuba) might assist the USSR orthe clandestine introduction of nuclear weapons into the US. Weunlikely on two counts- We doubt that either the Soviets or theseek to enlist the aid of another nation inensitiveif they should, that nation's leaders would almost certainlyroposal (hat could jeopardize their national survival merely toor Chinese policy.


the Soviets or Communist Chinese have considered the daitdestineof nuclear weapons into the US, they have almost certainlyby the same general considerations; the element of risk, thefor clandestine introduction, and the results that could betwo countries. JiOsvever. occupy vastly different strategic positionsUS. Thus, while we believe that neither would consider the use of this




lactic except in tho contextossible general war. diSfiting strategicmight lead the Soviets and the Chinese to see the clandestineol nuclear weaponsomewhat different light.

he USSR. The Soviet leaden, like those of the US, must take account oi the possibility of general war in their military planning In such planning, the Soviets would consider Ihe clandestine introduction of nuclear weapons into (he US. If at all, onlyupplement to the main altack by their large strategic attack forces. Because they have already achieved an assured retaliatorythey would probablylandestine emplacement dfort asuseful only in supporteliberate or preemptive Soviet attack and directed toward delaying orS retaliatory attack. Possible targets might include important government headquarters, ley military command and control facilities missile detection and tracking radars, and possibly some manned alert forces. The Soviets would recognize, however, that even if such an effort were successful, it could not prevent US retaliation or reduce it to an acceptable level.

n considering clandestine attackupplement to other weapons, the Soviets would have to weigh their ability to initiate such attack rapidly, with little preparation, and in close coordination with tlie main weight of attack. Thus, clandestinely introduced weapons would have to be in position at the time the attacks were launched. In the casereemptive altack, thewould not allow suflicleni time for the uitroducuon and debvery of such weaponsecision to preempt. To prepare for (lib contingency beforehand, the Sennets would have to accept (he risk of maintaining weapons in the US for an indefinite period of time These difficulties would not obtain if the USSR decided deliberately to initiate general wareriod of low tension, weapons could be introduced into theelatively short time before use. But the Soviets would have to consider the risk of jeopardizing the element of surprise on which this course of action relics, and that discovery mightUS preemptive attack which would he disastrous for the USSR. For these reasons, we think it unlikely that the USSR will attempt to introduce nuclear' weapons clandestinely into (he US.

ommurusf Chine. The Chinese have no capability at presentttack (he US with nuclear weapons. They probably have an ICBM system in (he early stages of development, which could become operational several years from now. But they may fear that when it docs the US anHballistjc missilewill have rendered it largely inefiective. In these cucirmstancea, they might see some advantages in dandestiaely introducing and em placing nuclear weapons in the US. Inasmuch as (bey could not deliver such as attackcale sufficientecisive military objective, their object wouldbe to deter the USourse ol action that gravely threatened their national security. Consequently, the most likely targels would be population centers.


learly, the Chinese would also see grave disadvantages inove. So long as the US was unaware of their existence, the concealed weapons would have no effect upon its actions. Indeed, the risk of their discovery would be an ever-present, continuing clanger to the Chinese themselves. Once the Chinese announced that nuclear weapons were empUced in the US. the announcement would touch off an intensive search and eatraordinary security measures.the Chinese could not be sure that the US would in fact be deterred. On the one hand, the US might corutder such an unverified announcementere bluff. On the other it might take the clandestine introduction of such weaponsasus belli and, having taken such action as it could to safeguard its population,evastating nuclear attack on

J It is conceivable that some Chinese regime might be willing to accept such risks of national destruction, but wc think It unlikely.

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Original document.

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