Page 26removing less survivable ones, while continuing to invest as necessary in the forces retained.
One further factor should affect future nuclear weapons choices: there is little need to match specific characteristics of Soviet nuclear deployments. Deterrence of nuclear war is not impaired if the nuclear deterrent systems of the United States and its adversaries are substantially different in type and deployment, so long as they are survivable. Different nations may best meet their nuclear systems' increasing need for survivability in diverse ways.
In this discussion, we turn first to the question of estimating the appropriate numbers of central strategic nuclear systems and then to sample survivable force structures.
Since the beginning of the Cold War, the United States acquired strategic systems on the basis of political assessments of what was necessary to deter a nuclear war with the Soviet Union under the worst case scenarios perceived by the United States at the time. The number of weapons systems procured resulted more from the perceived need for redundancy as a hedge against uncertainties than from the number of targets for these weapons. Providing the most effective employment of the available weapons inventory in terms of some generally stated national guidance set the plans for target coverage. Except in some special cases, the number of targets did not determine numerical weapons requirements.
Under the existing general guidance and given the existing weapons inventory, the U.S. list of targets to be threatened has included: (1) most Soviet nuclear and conventional forces against which nuclear weapons could be thought effective; (2) the industrial and logistical base for supporting and reconstituting these forces, which includes most of the Soviet urban-industrial complex; and (3) the significant targetable command and control and leadership elements. One official study put the number of targets in the 5,000-9,000 range. 1 Unofficial estimates of what a more limited but adequate target list might be have led to numbers in the 2,000-3,000 range. 2 Even within this latter set, there are significant diminishing returns (that is, substantially less important targets would be hit) as the number of targets increases within each category.
Given that not all weapons are reliable or available at all times, that not all delivery systems will survive attack or reach their target, and that some weapons are devoted to suppressing air defenses, there must be significantly more weapons than there are targets to be struck. The ratio of weapons-to-target is highest if it is derived using the assumption that the essential nuclear missions would have to be carried out from a peacetime, nonalert posture, after U.S. forces had suffered a full-scale Soviet nuclear attack. In