FOR the past 30 years, the doctrine of deterrence has lain at the heart of America's--and the world's--strategic thinking. This doctrine holds that should any nation launch a nuclear attack, enough of its victim's missiles would survive to destroy the aggressor. Anything that threatens to neutralize or eliminate one side's nuclear forces endangers this hair-trigger balance.

Ten years ago the United States and the Soviet Union agreed to severely restrict anti-ballistic missiles--anti- missiles, in essence--because it was feared that one power confident of its defensive forces might launch a pre-emptive nuclear strike against the other. Thus, when President Reagan revive the anti-missiles idea, this time in satellite form, it provoked immediate outcry from those who defend deterrence. In this light, it is easy to understand the alarm felt in American defense circles when it appeared that the Soviet Union had achieved first-strike capability--the ability to attack and wipe out our land-based nuclear forces--seriously eroding the credibility of the American deterrent.

Enter the MX--missile experimental--billed as the invulnerable missile needed to restore that credibility. Its chief virtue was to be a basing system that would shield or hide it from Soviet warheads. In addition, the missile boasted more warheads and improved accuracy.

Yet for the purely defensive purposes of deterrence, it would have sufficed to put the old-line Minuteman aboard the improved basing system--saving billions of dollars. And now a second presidential commission on the MX basing system has suggested that the new missiles be placed in the same Minuteman silos whose vulnerability prompted concern in the first place. How, then, is or was the MX necessary to preserve the U.S. nuclear deterrent?

Is a stronger and more accurate missile an inherently greater deterrent? Surely if the Russians knew that exactly ten U.S. missiles would survive their attack, the power and accuracy of these survivors might weigh in their strategy. As it is, however the Soviets did not and do not have the potential to eliminate any where near every U.S. land-based missile, not to mention the nearly one-third of our nuclear force secure from Soviet attack aboard submarines?

The United States would emerge from any nuclear attack with more than enough megatonnage to performance promised retaliatory destruction. And of course, the President would always have the option of launching our missiles before the Soviet missiles had even landed. The little black box is never more than seconds from the President, and missiles on the Siberia-to-Omaha run take thirty.

INDEED, a deterrent second strike is aimed not at hardened silos but at eminently vulnerable cities. If current missiles threaten to turn Moscow into a 600-foot crater, does the prospect of an 800-foot crater act as a substantially greater deterrent? The MX is tailor-made for one purpose the destruction of Soviet missiles in their silos.

Why, then, did the United States spend billions to develop this first-class, first strike weapon in the name of deterrence? The Pentagon might have been exploiting the Soviet threat to get the latest technological wonder; the power of the military-industrial complex feeds on fear. Yet this would indicate a terrifying disregard for the national defense and an unparalleled waste of tax dollars.

Another possibility is that there is a second, seldom articulated assumption of U.S. strategic policy--that America is a superpower capable of launching nuclear holocaust, and that we intend to remain one. The United States justifies a credible first-strike force--and its unwillingness to renounce the first use of nuclear weapons--as necessary to keep the vastly more powerful Soviet conventional forces at bay in Europe and elsewhere.

Yet we are assured on all sides that a nuclear war is "unwinnable." Why do we pour billions into developing a nuclear deterrent to the Warsaw Pact, while neglecting the immediate problem, the woeful state of our front-line conventional deterrent? The implication is that U.S. strategic thinking is stuck on the antagonistic notion of carrying the ultimate big stick.

If so, the MX gives the lie to Administration attempts to paint the Soviet Union as the "real" nuclear menace. The only thing more horrifying than the prospect of the United States fighting a nuclear war is the prospect of the United States starting one. Surely those games have been played out, where vastly outnumbered NATO forces are overrun in Europe and the last hope of the West is America's nuclear umbrella.

Whatever ultimately motivated the decision to build the MX, the missile now represents nothing more than an upgrading of the U.S. nuclear force to first-strike capability. As such it challenges the Soviet Union to yet another round of ever more costly missiles. The MX should be the first casualty of a careful analysis of America's defense needs.

As the Reagan Administration calls for a still greater assortment of wonder weapons, at still greater costs, the nation should be sure that peace remains an integral part of "peace through strength." And it should be sure that the proposed systems meet its defense needs in the most effective and direct manner. Where America relies on the nuclear deterrent to back its conventional troops, it should beef up those troops, not the weapons of last resort never designed to replace them.