A rational strategy for the employment of nuclear weapons is a contradiction in terms. The enormity of the destruction, either executed or threatened, severs the nexus of proportionality between means and ends which used to characterize the threat and use of force. This does not mean, however, that all nuclear strategies are equally irrational. The nuclear policy of the Reagan administration—which is essentially the same as that of the Carter administration and which has its roots in developments initiated by even earlier administrations—is particularly ill-formed. As I will demonstrate, the basic reason for this is that the strategy rests on a profound underestimation of the impact of nuclear weapons on military strategy and attempts to understand the current situation with intellectual tools appropriate only in the pre-nuclear era.American strategy for the past several years—the “countervailing strategy”—has been based on the assumption that what is crucial is the ability of American and allied military forces to deny the Soviets military advantage from any aggression they might contemplate. The U.S. must be prepared to meet and block any level of Soviet force. The strategy is then one of counterforce—blocking and seeking to destroy Soviet military power. The goal is deterrence. Although it is concerned with how the U.S. would fight many different kinds of wars, both nuclear and non-nuclear, it is not correct to claim that the strategy seeks to engage in wars rather than deter them.