"Mutual Deterrence" Speech by Sec. of Defense Robert McNamara

San Francisco, September 18, 1967

In a complex and uncertain world, the gravest problem that an American Secretary of Defense must face is that of planning, preparation and policy against the possibility of thermonuclear war. It is a prospect that most of mankind understandably would prefer not to contemplate. For technology has now circumscribed us all with a horizon of horror that could dwarf any catastrophe that has befallen man in his more than a million years on earth.

Man has lived now for more than twenty years in what we have come to call the Atomic Age. What we sometimes overlook is that every future age of man will be an atomic age, and if man is to have a future at all, it will have to be one overshadowed with the permanent possibility of thermonuclear holocaust. About that fact there is no longer any doubt. Our freedom in this question consists only in facing the matter rationally and realistically and discussing actions to minimize the danger.

No sane citizen, political leader or nation wants thermonuclear war. But merely not wanting it is not enough. We must understand the differences among actions which increase its risks, those which reduce them and those which, while costly, have little influence one way or another. But there is a great difficulty in the way of constructive and profitable debate over the issues, and that is the exceptional complexity of nuclear strategy. Unless these complexities are well understood rational discussion and decision-making are impossible.

One must begin with precise definitions. The cornerstone of our strategic policy continues to be to deter nuclear attack upon the United States or its allies. We do this by maintaining a highly reliable ability to inflict unacceptable damage upon any single aggressor or combination of aggressors at any time during the course of a strategic nuclear exchange, even after absorbing a surprise first strike. This can be defined as our assured-destruction capability.

It is important to understand that assured destruction is the very essence of the whole deterrence concept. We must possess an actual assured-destruction capability, and that capability also must be credible. The point is that a potential aggressor must believe that our assured-destruction capability is in fact actual, and that our will to use it in retaliation to an attack is in fact unwavering. The conclusion, then, is clear: if the United States is to deter a nuclear attack in itself or its allies, it must possess an actual and a credible assured-destruction capability.

When calculating the force required, we must be conservative in all our estimates of both a potential aggressor's capabilities and his intentions. Security depends upon assuming a worst plausible case, and having the ability to cope with it. In that eventuality we must be able to absorb the total weight of nuclear attack on our country -- on our retaliatory forces, on our command and control apparatus, on our industrial capacity, on our cities, and on our population -- and still be capable of damaging the aggressor to the point that his society would be simply no longer viable in twentieth-century terms. That is what deterrence of nuclear aggression means. It means the certainty of suicide to the aggressor, not merely to his military forces, but to his society as a whole.

Let us consider another term: first-strike capability. This is a somewhat ambiguous term, since it could mean simply the ability of one nation to attack another nation with nuclear forces first. But as it is normally used, it connotes much more: the elimination of the attacked nation's retaliatory second-strike forces. This is the sense in which it should be understood.

Clearly, first-strike capability is an important strategic concept. The United States must not and will not permit itself ever to get into a position in which another nation, or combination of nations, would possess a first-strike capability against it. Such a position not only would constitute an intolerable threat to our security, but it obviously would remove our ability to deter nuclear aggression.

We are not in that position today, and there is no foreseeable danger of our ever getting into that position. Our strategic offensive forces are immense: 1,000 Minuteman missile launchers, carefully protected below ground; 41 Polaris submarines carrying 656 missile launchers, with the majority hidden beneath the seas at all times; and about 600 long-range bombers, approximately 40 percent of which are kept always in a high state of alert.

Our alert forces alone carry more than 2,200 weapons, each averaging more than the explosive equivalent of one megaton of TNT. Four hundred of these delivered on the Soviet Union would be sufficient to destroy over one-third of her population and one-half of her industry. All these flexible and highly reliable forces are equipped with devices that ensure their penetration of Soviet defenses.

Now what about the Soviet Union? Does it today possess a powerful nuclear arsenal? The answer is that it does. Does it possess a first-strike capability against the United States? The answer is that it does not. Can the Soviet Union in the foreseeable future acquire such a first-strike capability against the United States? The answer is that it cannot. It cannot because we are determined to remain fully alert and we will never permit our own assured-destruction capability to drop to a point at which a Soviet first-strike capability is even remotely feasible.

Is the Soviet Union seriously attempting to acquire a first-strike capability against the United States? Although this is a question we cannot answer with absolute certainty, we believe the answer is no. In any event, the question itself is -- in a sense -- irrelevant: for the United States will maintain and, where necessary strengthen its retaliatory forces so that, whatever the Soviet Union's intentions or actions, we will continue to have an assured-destruction capability vis a vis their society.