Useful guidelines amid the hassle over strategy

While prompted by the MX dispute, the President's Commission on Strategic Forces had a wider charter: to review the purpose, character, size, and composition of US strategic forces. Accordingly, besides its proposal for deploying 100 MX missiles, the commission undertook a more basic analysis of the direction for such forces and for arms control. Its report offers some useful criteria for both.

Such guidelines are badly needed. The debate over defense and arms control could hardly be more muddled or confusing than at present. The battle on the defense budget is conducted almost wholly in terms of the percentage of increase rather than the role and need for specific weapons. The House appears to favor a fuzzy resolution for an ''immediate'' freeze on nuclear systems. Others espouse a doctrine of ''no first use'' of nuclear weapons. The issue of theater nuclear weapons is divisive within NATO. The Arms Control and Disarmament Agency is in disarray. And the proposals for strategic arms control in START inspire little confidence or support.

These issues, like the hassle over MX, reflect deep divisions and confusion over the premises and direction of our military strategy. There is no consensus to serve as a baseline or framework for assessing specific proposals and weapons. The default starts with the Pentagon, which has failed to put forward a convincing strategy or rationale to govern the choice of weapons and forces and as a basis for arms control.

Nor have the critics done better in this regard. The proponents of the nuclear freeze, or of no first use and other specific measures, have relied more on slogans like ''end the arms race'' and on justified revulsion against nuclear war than on analysis of how such measures would serve long-term interests.

The analysis of the report could contribute to more constructive debate and decisions.

First, it stresses that our aim must be to prevent any major war, since a conventional war entails the gravest risk of escalating into nuclear war. At the same time that risk bolsters the deterrent against initiating any aggression. (Thus a doctrine of no first use, while likely to be ineffective, could increase the danger of conventional aggression. Conventional forces should be strengthened but as part of a combined deterrent.)

Second, the report recognizes that the viability of the strategic deterrent depends on the combination of its various components - ICBMs, sea-based missiles , and bombers. Even if one leg is vulnerable ''in isolation'' (as our land-based ICBMs are), the deterrent will remain effective as long as the other two are secure. Thus the ''window of vulnerability'' is theoretical, not actual.

Third, a primary objective for strategic forces and arms control should be to enhance the stability of deterrence, especially in crises. The gravest danger of war could arise from mistake or misjudgment resulting from a perceived need to preempt. Fixed, land-based ICBMs with MIRVs tend to be destabilizing: their multiple warheads make them lucrative targets, vulnerable to one or two accurate attacking missiles. Sea-based systems and bombers are more secure and less threatening.

Based on this reasoning, the commission urges the development of a small, mobile single-warhead ICBM as well as a smaller missile-sub as a follow-on to Trident. Moreover, arms-control proposals should be designed to encourage the shift away from land-based MIRVs, as by imposing constraints on warheads rather than launchers. (A nuclear freeze would, of course, forestall such adaptation.)

This analysis, while not novel, makes good sense. Yet in addressing the specific issue of MX, the commission takes a different tack. This massive, fixed-based missile, with 10 warheads, hardly fits its prescription. The report justifies it as an interim response to the gurrent situation, relying on several grounds which vary in plausibility.

The argument that the Soviets are unlikely to negotiate constraints on their SS-18s and 19s unless the MX is available as a bargaining chip may have some merit. But one may doubt whether the Pentagon will favor the trade-off, once the MX program is under way. The claim that canceling MX now would be seen by the Soviets as a lack of national will seems more questionable: perhaps, if the cause were domestic divisions; hardly, if it resulted from a reasoned decision. The third main argument, that it is essential to rectify the imbalance in hard-target capability in order to deter the Soviets and reassure allies by having a credible capacity for controlled limited attack on hard targets, seems somewhat inconsistent with earlier parts of the report. It seems improbable that the present situation would tempt the Soviets to be less cautious.

Aside from the MX issue, the proposals of the commission are likely to face substantial obstacles. The move to a small, single-warhead missile may not be well received by the Air Force, according to some reports. It does raise some real questions about costs, mobility, and numbers, especially if constraints on warheads cannot be negotiated with the USSR. And with their heavy commitment to the SS-18 and 19 (and perhaps newer versions), the Soviets are likely to be slow to move toward smaller or un-MIRVed land-based missiles.