MX: the need to link arms and arms control

It is necessary now to make sure that the US nuclear arms control position and nuclear weapons posture remain consistent, mutually supportive, and reconcilable.

This is not to say that it is a good idea to stop development of any weapons system that we seek to eliminate from world inventories through negotiation. For example, consistency does not require that the United States terminate production now of intermediate-range nuclear weapons systems - the Pershing II and ground-launched cruise missile - because our negotiation stance with the Soviets is to eliminate such systems entirely.

There may be independent reasons for delay or termination, but the credibility of such a negotiation may be enhanced, not reduced, by continuing development or production. This is particularly true where we are asking the Soviets to sacrifice an already deployed system in exchange for a US system not yet produced.

The notion that our nuclear forces be reconcilable with and mutually supportive of an ultimate set of arms control treaties requires a far more subtle consistency. It means that force structure and weapons systems planning must remain compatible not only with existing treaties but also with the range of likely and attainable arms control outcomes.

However, we cannot accept or even entertain a treaty that creates or leaves unsolved military problems that are not susceptible to technical, budgetary, and politically acceptable solutions with a time frame essential to national security requirements. Such a reconciliation is very difficult in a highly charged political and diplomatic context.

In my view, we made a serious mistake in the last administration in failing to embrace an obvious interdependency. Our military solution to ICBM vulnerability - a finite number of deceptively based MX missiles - depended upon a successfully concluded SALT II treaty that bounded the size of the theoretical threat to our ICBM systems.

With the abandonment of the SALT II ratification effort, we were left in the position of espousing a weapons system that was necessarily open-ended in scope. Moreover, it was uncertain that it could permanently meet an unbounded threat.

In the world of military analysis, we could theoretically run out of suitable land for deployment before the Russians ran out of their ability to produce warheads. In the world of ordinary people, the American public had no appetite for the dedication of unlimited amounts of open land and federal funds to a system that could not be shown to be sur-vivable.

While serious analysts may question whether the problem of ICBM vulnerability is more than theoretical, military planners have made the case that, however improbable, what could happen (if everything went perfectly in an unprecedented complex attack) might happen and must be addressed.

For the purpose of this argument, put aside the debate over the doctrine of mutual assured destruction - i.e., that the threat to attack Soviet cities with whatever weapons remain after a first strike is or is not sufficient deterrence. Put aside also the argument that sufficient deterrence exists in the uncertainty that we would launch under attack or reliable warning. If national policy remains that neither of those positions provides a flexible option or sufficient credibility, we are left with an unsolved problem.

We are now facing a solution to ICBM vulnerability that may be inconsistent not only with future arms control treaties but with one of the few permanent treaties we have with the Soviet Union. The consensus of a highly cautious community of nuclear effects analysts appears to be that closely spaced basing (CSB) for MX - also known as ''dense pack'' - is theoretically survivable with a not yet attained but possibly technically achievable ballistic missile defense. Such defense, when details of optimum system size are explored, may require renegotiation or abrogation of the ABM treaty. That treaty limits deployment of antiballistic missile systems to one site and circumscribes launcher missile radar numbers, and to some extent technology.

Moreover, both the SALT I Interim Agreement and SALT II prohibit the construction of new silos. Although the first has expired and the second was never ratified, the President has announced our willingness to abide by the terms of SALT II, so long as the Soviets do. It may be that possible agreed interpretations would enable the CSB shelter to be treated as something other than a silo, but that is not an apparent interpretation now.

Then, system growth beyond 100 missiles in 100 shelters is anticipated to counter foreseeable Soviet steps to defeat our newly achieved survivability. Some analysts insist that, to be sure of survivability, we must plan for a total system size of 300 in three locations even with ballistic missile defense.

With 10 warheads on each missile adding up to 3,000, this presents a built-in conflict with the President's START proposals, which provide for a total of 5, 000 warheads, with 2,500 on land-based ICBMs. Further technical work might prove a system of such a size unnecessary, but the congressionally imposed deadline for Department of Defense decision by December 1982 prevents continued work to reconcile survivability with past and future arms control.

There are several ways out, none really satisfactory.

We could proceed, and face all the in-consistencies just described.

Or the MX program could be canceled. Given the unpopularity of the program, that is not unlikely. But it would be a mistake, for several reasons:

First, our negotiating position in START would be weakened by abandoning a threatening system without requiring a corresponding reduction in Soviet nuclear threat to us.

Second, MX represents a needed and highly successful modernization program for 20-year-old missiles. These missiles are a crucial element of our present nuclear deterrent policy, but their maintenance daily becomes more of a problem.

Third, cancellation of MX would imply that we have given up on the question of ICBM vulnerability before we have any indication that the issue might have been solved by system design in combination with treaty-imposed restraints.

A better approach would be to move into MX production, test the missile on schedule next January, but with only three warheads instead of the 10 that it is designed to carry. Then it could be deployed in Minute Man silos replacing the least capable and most obsolete missiles first, as practicable.

Under SALT counting rules, the solution would violate neither agreement, and such an initial deployment leaves open a wide range of future negotiating and deployment options. It is true that it offers lesser capability than the Air Force feels is required; and, if negotiations fail, it would take time to produce and test additional warheads. But it offers a system that is politically achievable now, and can move ahead quickly.

CSB is likely to meet the same fate as MPS, the deceptive basing mode. But both the present US and USSR proposals would accommodate the program I propose. It would allow time to work hard on the best technical permanent solution to survivability, both in the context of a permanent treaty and without presenting to the Soviets an unnecessary first strike threat while we are negotiating in good faith.

Such a step will only be possible if the President provides clear direction to the warring factions in State and Defense Departments that the cooperative goal must be a survivable triad in the context of an achievable permanent strategic arms control agreement.