Case 2: Some Promise

Suppose it soon becomes widely apparent both inside and outside the defense establishment that the current program may eventually lead to strategic defenses that are reliable, survivable, and cost-effective, even in the face of the first round of likely countermeasures—but, alas, clearly far from perfect. That is, suppose it remains as obvious as it is today that even if a BMD system fulfills the Nitze criteria, there would still be so many pathways through it and around it that the United States and its allies would continue to be threatened with great, probably total, destruction. Most analysts believe that even this more modest outcome is very unlikely; but, conceivably, it could come to pass. Let us suppose it does.

Then, as in Case 1, the United States would, and under certain conditions probably should, go ahead with the program on an accelerating basis. The usefulness of cost-effective but imperfect defenses has been much discussed. In general, even quite imperfect defenses can make preemptive attacks more uncertain and more difficult. If, for example, active defenses are deployed to protect the retaliatory forces, the attacker must increase the size of his strike in order to bring the potential result back to the level that had existed before the deployment of defenses, and he cannot be fully confident of doing so even then. (So-called preferential defenses, to be described in the next chapter, in which only certain specific, but unidentified, units of the retaliatory forces are in fact defended, greatly exacerbate this problem.) The same consideration applies to the defender's command-and-control system. If an attacker believes he knows where the defender's vital control units are located, then, in the absence of defenses, he can at least calculate that a certain

level of attack would destroy them all. In the presence of even partially effective defenses, he can no longer be sure of doing so. Given the size of today's forces, even a relatively small remnant is easily sufficient to threaten annihilation of the attacker's cities and population, and this remains so even if the attacker has the same imperfect defenses. Thus, improving the survival chances of even a modest remnant of the defender's forces reinforces deterrence.

In sum, the potential value of imperfect but robust and cost-effective defense lies in the fact that such defenses would in general reinforce deterrence. Thus, the probability of an attack would be reduced even if the defenses could not adequately blunt the attack on cities and population. There are, however, alternate means for reinforcing deterrence. Besides, simply meeting the Nitze criteria is not enough by itself to justify building active defenses. These alternative means in general are also based on increasing the survivability of the various elements of the deterrent forces, including especially the command-and-control system. For the immediate future, the most promising appear to involve better protection of national-command authorities and the further application of mobility, dispersal, and other forms of deception to render retaliatory forces untargetable. Active defenses, if they are to be deployed, would in general have to be cheaper than the alternatives to make them worthwhile.

But if strategic defenses were to hold promise of eventually surpassing the Nitze criteria by a substantial margin, and not merely meeting them on an equal cost basis, the United States would probably choose to go ahead with them even if there were other ways to make offensive forces more survivable. In such a case, the deployment of strategic defenses might well lead to a world in which there was progressively more emphasis on defense than on offense. Some sort of useful transition away from the current dreadful situation—in which peace is based mainly on the threat of mutual suicide—might occur. Such a transition is too far off and too speculative to foresee its details, but it might include such things as substantial arms reductions, a defense-protected build-down, and a general shift away from the current high-strung nuclear confrontation with all the extraordinary dangers inherent in it.

Such an outcome also seems to us and to most defense analysts to be very unlikely. But the possibility, however slight, that it might emerge is one of the important reasons that many of the defense experts who oppose the current SDI program, with all the rhetoric and politics that have surrounded it, endorse a substantial, continuing research program

in all areas of defense technology, including its newest and most exotic forms.