In both his State of the Union and Second Inaugural addresses, the President has extolled the prospect of a new strategic defense system in space (known as ``star wars'') that would put an end to the threat of nuclear war. The presentation of this wishful hope in the earlier address was particularly seductive -- viz., ``I have approved a research program to find, if we can, a security shield to destroy nuclear weapons before they reach their target. It won't kill people, it would destroy weapons. It wouldn't militarize space, it would demilitarize the arsenals of the earth. It would render nuclear weapons obsolete.'' All of this sounds wonderfully comforting and so has great appeal to audiences haunted, as we all are, by the specter of nuclear holocaust -- despite the fact that it is a dangerous delusion.
All of the evidence of history since men invented weapons is that every defensive advance calls forth new ways of knocking down or getting around that defense. Forts brought into play siege machinery; armor, the crossbow, and later the musket; foxholes and trenches and bunkers, the hand grenade and later napalm; the Maginot Line, new capabilities of armored maneuver; reliance on the protection of distance, the airplane and later the missile; hidden nuclear weapons development, the spy satellite as the eye for offensive countermeasures, if need be. The examples could be multiplied manyfold. The sad fact of human experience is that no defense is sure for very long and that the best defense has usually proved to be not finally a shield but ways to get past whatever the shield of the time happens to be.
Thus what the President's hope for a ``security shield'' promises is not, in fact, eventual demilitarization or even enhanced security. Neither, assuredly, does the SDI mean reduced defense expenditures when the research phase alone is said to be estimated at $26 billion over five years. What one must foresee instead is an accelerated upward spiraling of cost and of effort, on both sides, to counter existing offensive capabilities with new defensive measures and to outmaneuver the latest defenses with still more devious offensive means.
The dangers inherent in the nuclear arms race of the superpowers should be seen to be too enormous and too pressing for wishful thought. A more promising course is to preserve the existing agreements that are serving to put some limits on both offensive and defensive nuclear arms development (the Limited Test Ban Treaty, ABM Treaty, SALT I, and SALT II), while negotiating earnestly and in good faith for a Comprehensive Test Ban, a build-down agreement, and other ways to reduce existing nuclear arsenals. Robert F. Goheen Senior fellow, Woodrow Wilson School of Public and International Affairs Princeton University Princeton, N.J.