Foreign Relations of the United States, 1951, Europe: Political and Economic Developments, Volume IV, Part 2

No. 876

INR files, NIE series

National Intelligence Estimate¹

secret
NIE–29

[Washington,] March 20, 1951.

Probability of an Invasion of Yugoslavia in 1951

the problem

To assess the capabilities and intentions of the USSR and its European Satellites with respect to action against Yugoslavia during 1951.

conclusions

1. The ultimate Soviet objectives in Yugoslavia are to eliminate the Tito Government, to replace it by a regime subservient to the USSR, and to integrate Yugoslavia politically, economically, and strategically into the European Satellite structure. The USSR has not, however, indicated that it intends to try to eliminate the Tito regime regardless of the cost or within any specific period of time.

2. It is unlikely that during 1951 the Tito regime could be overthrown by a Soviet-inspired coup or by internal revolt. Therefore, the USSR would have to resort to Satellite or Soviet-Satellite invasion if it intended to overthrow Tito in 1951.

3. The continuing military build-up in the neighboring Satellite states (increase in armed forces, stockpiling, re-equipment, gasoline conservation, stepping-up of war industry, etc.) has reversed the previous balance of military strength between the Satellites and Yugoslavia and has given the Satellites the capability of launching a major invasion of Yugoslavia with little warning.

4. A major, sustained invasion of Yugoslavia employing the Satellite armies under Soviet central direction and given full logistical support by the Soviet Union has the capability of forcing the Yugoslav Army back into the mountainous region along the Adriatic and of gradually extending control of the principal communication lines to the major centers of that redoubt. The Yugoslavs would continue to resist, however, and would conduct guerrilla operations long after the collapse of formal military resistance.

5. Combined Soviet-Satellite forces could successfully invade Yugoslavia, overcome formal military resistance, and eventually render guerrilla operations ineffective.

6. Yugoslav capabilities and morale are such that substantial and continuing Western assistance in military supplies and equipment would probably enable Yugoslavia to maintain organized resistance to a Satellite attack indefinitely, at least in the mountain area. Such assistance could extend the period of resistance even in the case of a full-scale Soviet-Satellite attack. Any Western matériel sent would have to be adapted to the special requirements of Yugoslav forces. Moreover, to be effective to Yugoslavia in the initial stages of an invasion, it would have to be delivered well in advance of hostilities.

7. Continuing large-scale Satellite military preparations indicate that the groundwork is being laid for a possible invasion of Yugoslavia. These indications do not, however, provide conclusive evidence of an intention to attack Yugoslavia since there has been a military build-up in the other Satellite states in addition to the ones adjacent to Yugoslavia and since, in the case of Bulgaria and Albania, the military preparations could point to an attack on Greece or Turkey as well as Yugoslavia. Moreover, there is no conclusive evidence that military preparations pointing toward a Satellite attack on Yugoslavia are timed for an attack in 1951. Cominform propaganda since July 1950 has consistently advanced arguments that could be used to justify a Satellite attack on Yugoslavia, but there has been no recent trend in such propaganda suggesting an attack at an early date.²

8. On the basis of intelligence available we are unable to determine whether the Kremlin has made a decision to attack Yugoslavia. The Kremlin may estimate that in 1951 such an attack by the Satellites could be carried through successfully without incurring effective Western intervention or precipitating general war. On the other hand, the Kremlin may estimate that the Western Powers would give largescale support to Yugoslavia, in the event of an attack, thereby making the operation difficult and costly and creating a greater risk of general war than the USSR was willing to accept. Finally, the Kremlin may be fully prepared for the eventuality of general war and may launch an attack on Yugoslavia regardless of the risks involved. Although it is impossible to determine which course the Kremlin is likely to adopt, we believe that the extent of Satellite military and propaganda preparations indicates that an attack on Yugoslavia in 1951 should be considered a serious possibility. We believe further that such an attack, if launched, would be made by Satellite forces with “unofficial” Soviet assistance as required.³

[Here follows the remainder of this estimate, a five-page section entitled “Discussion”, elaborating on the conclusions outlined above.]

1. For information concerning the preparation of National Intelligence Estimates, see footnote 1, Document 613. On the covering sheets attached to the source text, it was noted that this estimate had received the concurrence of all members of the Intelligence Advisory Committee and that it was based on information available on March 15.

2. On May 4, NIE–29/1 (“Review of the Conclusions of NIE–29 ‘Probability of an Invasion of Yugoslavia in 1951’”) was issued and it contained the following summary:

   “There have been no major changes in Soviet strength or dispositions that bear upon the likelihood of an attack by Soviet forces in 1951. However, Satellite capabilities for initiating an attack on Yugoslavia with little or no warning have increased, and Satellite military preparations are continuing.” (INR files, NIE series)

3. In an Intelligence Estimate prepared by the Office of Intelligence Research in the Department of State and circulated as I.E. No. 16 of March 5 (“Extimate of Probable Western and Soviet Reaction to Alternate U.S. Policies Concerning an Attack on Yugoslavia in 1951”), the following conclusion was made:

   “U.S. warnings would probably not prevent a Soviet-supported Satellite attack on Yugoslavia since Soviet decisions concerning such an attack would be controlling and since any Soviet decision in favor of such an attack would have taken into consideration the strong possibility of U.S. intervention. A major U.S. program of logistic aid designed to build up military strength in Yugoslavia and throughout the Eastern Mediterranean might well, however, stimulate a Kremlin decision in favor of an early Soviet-supported Satellite attack on Yugoslavia.” (768.5/3–551)