Why the US needs the MX in its future

The American government tends not to be very adept at explaining either its strategy or its major weapon choices to the public. Nowhere is this more apparent than with respect to the MX ICBM. Three US administrations, of very different political hues, have endorsed the MX missile for a set of reasons that merit wider dissemination than they have been allowed.

Three classes of questions are relevant to thinking about the MX, and each has played, and continues to play, its own unhelpful role.

First, MX suffers from guilt by its association with nuclear war - which everybody can agree they are against. Unfortunately, it is too little appreciated that nuclear weapons cannot be disinvented and the only theory of peace available is nuclear deterrence. In a perfect world there would be no need for MX missiles, or indeed for weapons of any kind, but reflections of that kind are profoundly irrelevant to the policy choices we face today.

The ''freeze now'' movement appears to believe that it is making a moral gesture against nuclear war. That movement declines to acknowledge that freezing or even reducing nuclear weapon stockpiles would, at best, be close to irrelevant to the risks of war occurring.

In practice, it is more likely that ''freezing now'' would risk increasing the possibility of war because it would freeze out solutions to acute strategic problems that currently exist. The land-based Minuteman ICBM is near totally vulnerable now - so freezing now would simply lock in that very destabilizing condition - while our frozen bombers and missile-launching submarine forces would have to contend with improving, and unfrozen, Soviet air defenses and antisubmarine warfare capability.

The US government is recommending deployment of MX in order to recover some dangerous lost ground in the quality of the US deterrent. The fact that we must rely upon nuclear deterrence is indeed regrettable, but it is necessary and morally defensible.

Second, controversy continues on the subject of what US nuclear strategy should be. The MX missile, which is designed to be able to destroy very hard Soviet targets (such as missile silos and military and political command facilities), is criticized for being a war-fighting instrument rather than an instrument of deterrence.

Nothing could be further from the truth. For many years, the US government has understood that deterrence cannot be simply based upon the ability to bring on a holocaust. For a threat to be believable, and thus an effective deterrent, it has to posit purposive military actions and those actions have to be directed aganst targets that are of very high value to Soviet leaders.

The MX missile is a vitally important part of the US deterrent to nuclear war. Soviet leaders should be deterred from fighting if they are not convined that they can win - if they lack a ''splendid superiority'' in key measures of relative military prowess. The MX should have the very stabilizing effect of ensuring Soviet doubts about their ability to win a nuclear war.

The MX ICBM should function as a roadblock to war. It would constitute a threat to most of the throwweight of the Soviet strategic forces (nearly 75 percent of which is concentrated in silo-based missiles) and to politically very sensitive command and control targets, while it would not invite a Soviet first strike because of its survivable basing. The nuclear-armed missile, in Soviet eyes, is at the heart of the contemporary ''revolution in military affairs.''

The MX missile will be the single most potent weapon in the US arsenal. MX deployment will mean that Soviet military planners will have to admit to their political leaders that a highly credible threat to the most important Soviet values cannot be neutralized. Anyone who has a care for deterrence stability should be on the streets demonstrating for the MX missile.

Third, the strategic merits of MX for the stability of deterrence and for the prospects for crisis control continue to be upstaged by the seemingly endless controversy over the basing mode issue.

If any issue of military engineering has been studied carefully, it is MX basing. The multiple protective structure (MPS) basing mode bequeathed by Carter to Reagan was ''good enough'' to do the job and so, on the evidence thus far available, is the latest proposal for closely spaced basing (CSB).

The MX missile offers unique qualities of accuracy, reliable command and control, flexibility, security, and operational readiness. Those qualities are needed to deter a Soviet Union that has a well-developed theory of victory in nuclear war.