170. Memorandum From the Ambassador at Large (Thompson) to the President’s Special Assistant (Rostow)1

The difficulty of predicting Soviet reactions is compounded by the fact that in the period since the end of the war, their reaction to actions on our part which were known to them were not what we would consider rational or called for in the circumstances. Soviet assessment of a U.S. deployment of a significant ABM system will vary considerably, pending upon whether we were reacting to a major Soviet deployment or whether we had initiated this new step in the arms race. I do not believe we can consider it as established that the Soviets have at this time decided upon a major ABM deployment. The Soviets have clearly embarked upon a plan to increase the number of their ICBMs and to deploy many of them in hardened sites. I believe they will carry this plan to completion.

If we initiate major ABM deployment, I feel confident that the Soviet response in the first instance would be to do likewise rather than to increase the number of their ICBMs beyond already planned levels. I would doubt that the Soviets could both deploy a major ABM system and increase ICBMs beyond planned levels without taking drastic action in some other field, such as suspending their space program.

If it is clearly the Soviets that initiate ABM deployment and we respond with a similar system, I would even more doubt that they would increase their offensive weapons beyond planned levels during the next five years or so because of the pressure upon their resources of other important programs in the non-military field. I think it quite likely, however, that as the significance of our planned improvement in the quality [Page 410]of our offensive capability becomes increasingly clear to them, they may respond with a similar program of qualitative improvement. I would expect that in any of these situations, the Soviets would increase their submarine launched missile capability.

Since the last war, whenever the Soviets have been faced with a choice between the development of offensive or defensive capability, they have generally opted for the defensive. This can partly be explained by their belief in their own ideology, which postulates that Communism would inevitably spread over the entire world and that the principal military problem for the Communist countries is to protect themselves from the danger that imperialism in its death throes might lash out against them in a desperate military gamble.

Given the economic problems which the Soviets already face in the allocation of their resources, which are insufficient to meet their goals, I believe that their civilian leaders would welcome an opportunity to avoid incurring the enormous expenditure which the deployment of a major ABM system would entail, at least over the next few years. On the other hand, the civilian leadership is weak in comparison to past regimes and it seems probable that this has automatically increased the relative influence of the Soviet military.

As the Soviet military acquire knowledge of the qualitative improvement in our ICBMs, they may well argue that an ABM system is essential to offset or at least raise doubts in our minds as to the efficacy of our offensive capability, since we could never be sure how effective their ABM system was. On balance, however, I believe we have a good chance of negotiating an ABM,ICBM freeze.

  1. Source: Washington National Records Center, RG 330, OSD Files: FRC 70 A 4662, 471.94, ABM, November-December, 1966. Top Secret. A stamped notation on the source text reads: “Mr. Vance has seen.” For context of this memorandum, see footnote 2, Document 169.