Upsetting a Delicate Balance

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For such an arrangement to be truly an improvement on the current "offense- dominated" form of mutual deterrence, there would have to be a delicate and mutually recognized balance between too little defense and too much. There would also have to be rules to make sure that neither side stepped over the line. Each side would have to be confident that its own defenses constituted adequate insurance against the threat of pre-emption; at the same time, each side would have to be just as confident that the enemy's defenses were not too extensive. Reason: if the enemy were not just safe from pre-emptive attack but invulnerable to retaliation, it would enjoy a considerable military and political advantage.

Thus strategic defenses, in order to be "stabilizing," must as much as possible discourage either side from being tempted to try a first strike while at the same time leaving both sides the capability of delivering a second strike. Otherwise, the side that fears its second-strike capability is in doubt will build up its offensive forces, in which case the other side will bolster its defenses even further, and a vicious circle will be under way.

That is the nub of one objection to Star Wars: some time between now and the idyllic, nuclear-free future, the U.S., without meaning to, will provoke the Soviet Union into what is sometimes called an "offense/defense spiral." To be in the coils of such a spiral would be far more expensive, and far more dangerous, than the MADness of the present.

The Soviets could compete in both offense and defense, and indeed are already vigorously doing so. While General Nikolai Chervov, the chief of the directorate of the Soviet General Staff that deals with arms control, has warned that Moscow is able to match any U.S. program, he has claimed that the U.S.S.R. will not try to deploy a Star Wars system of its own even if the U.S. does. Instead, he says, his country will do "everything possible" to undermine the effectiveness of American defenses. Georgi Arbatov, director of Moscow's Institute for the Study of the U.S.A. and Canada, made a similar point in an interview with TIME Moscow Bureau Chief Erik Amfitheatrof. "If you start to build Star Wars," he said, "we will be obliged to build new nuclear weapons, and more of them, which can penetrate your defensive shield."

That is not an idle threat. In nuclear one-upmanship, the advantage has always rested with the offense. That is a function partly of the sheer destructiveness of nuclear weapons. The Royal Air Force managed to defeat the Luftwaffe in the Battle of Britain by downing only a small fraction of the bombers that attacked on each sortie, but in a nuclear war, even a kill rate of 90% or higher in stopping enemy warheads would be insufficient, given the vast destruction that would be caused by the few that got through. Besides, space defenses might be vulnerable to antisatellite weapons, orbiting "mines" and other devices. Moreover, it is easier and cheaper to hurl extra warheads than it is to bolster a defensive system that can detect the attack, distinguish real warheads from decoys and intercept them in the minutes or seconds before they reach their targets.