13. Memorandum From Philip Odeen of the National Security Council Staff to the President’s Assistant for National Security Affairs (Kissinger)1


  • Minuteman Survivability and SALT

As you know, virtually all of our analysis of the strategic consequences of SALT rest on calculations of Minuteman survivability. In part this reflects real concern over the vulnerability of our ICBMs. But in part it is because it is one aspect of the problem that is readily calculable.

Because of the great attention given these calculations, I want to give you my views on:

—Whether the calculations are realistic;

—What they really mean, particularly for our position in SALT.

Are the Calculations Realistic?

There are three issues here:

—Are the threats realistic?

—Are the attacks realistic?

—Is it realistic to exclude SLBMs?

Threats. We have been using extremely advanced Soviet threats. This is justified on the grounds that we are seeking permanent agreement. The effect, however, is to exaggerate the time when Minuteman will become highly vulnerable, and to obscure the near and medium term effects of certain SALT limits (such as a ban on heavy ICBM MIRVs). In the long run, however, the message is clear: both sides will have forces capable of attacking fixed ICBMs.

The Attacks. The JCS is making a strong pitch that an effective first strike on Minuteman is extremely difficult, if not impossible. Such an attack must be very carefully timed and carried out. For practical reasons all the attacking weapons cannot arrive simultaneously. Therefore, the attack must be precisely spaced, in time and in the order of targets attacked, so that succeeding RVs are not killed nor their accuracy significantly degraded by earlier explosions. There is a big debate in the Pentagon over this issue, with OSD trying to minimize the problem. But the main implication is that our calculations are too pessimistic [Page 43] and the task of eliminating Minuteman is much more difficult than our analysis assumes.

Role of SLBM. In our calculations, we always consider ICBMs against ICBMs; SLBMs are left aside. In fact, however, we target Poseidon on Soviet silos and they may do the same, at least in the future. One can argue over whether it makes sense to use up SLBM forces for this purpose, but it is possible, and even reasonable, if there are a large number of SLBM RVs. If the Soviets do this, the long term effect could be to decrease further the survivability of Minuteman.

What Does Minuteman Vulnerability Mean?

On balance, we will have to count on Minuteman becoming quite vulnerable over the next two decades if the Soviets choose to make the required counterforce effort.

This does not mean that what we have called crisis stability will necessarily be undermined. First, we will have more than 5,000 highly survivable missile warheads at sea. Second, it is not clear what the Soviets could gain by attacking first.

The decision to embark on nuclear war will have more important issues to consider than the question of what fraction of the USSR ICBM force is required to destroy a given fraction of the U.S. ICBM force. Once a decision to engage in nuclear war is made, such considerations might become important (an attack on Minuteman might be a major flexible response option) but a decision to strike first, based largely on vulnerability calculations, is simply unreal.

On the other hand, as and when Minuteman becomes vulnerable we will have a problem we did not have before. We can have endless arguments over how important the problem is, but the main fact is that the strategic situation will have changed, and not for the better.

As a result, there will be inevitable pressure to deploy new systems to provide greater survivability. That is what the argument over land mobile ICBMs in SALT is all about; OSD does not want to foreclose this survivability option. That is what the debate over throw weight should also be about. Should we get into an aggregate ICBM and SLBM throw weight deal, if this inevitably reduces our flexibility to move to sea—an option that at this point looks more attractive than land mobile ICBMs.

Survivability and SALT

Thus, a main issue we face in SALT is whether we can postpone and discourage the development of ICBM killing counterforce while keeping open our options to respond to such a threat if it develops. In fact, keeping open such options is one aspect of discouraging such developments.

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A second order issue is how to avoid a SALT deal which has unequal effects on the survivability of the two sides. We do not want a deal (such as a land-based MIRV ban with unequal numbers and throw weight freeze) that will leave our ICBMs vulnerable in the long run but keep the Soviet ICBM force highly survivable.

To meet these problems, OSD basically wants to use SALT as a means of joint U.S. and Soviet strategic planning. They want to negotiate changes in the force structure of both sides so as to enhance long-term U.S. and Soviet ICBM survivability. While this is a laudable objective, it is probably unrealistic at this stage in our relationship with the Soviet Union.

What we can do is take more modest steps (partial MIRV ban, ceiling on ICBM throw weight). This can lay the foundation, and buy time, for the kind of negotiation in the future that OSD wants, while protecting our survivability options so that we can deal with the Minuteman vulnerability problem unilaterally if need be.

  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 888, SALT, SALT TWO–I–(Geneva), November 21, 1972–March 1973. Secret.