Righting the arms imbalance

There is still time for the United States to decide on a sensible policy toward the nuclear-missile issue in Europe. No irreversible step will be taken until December of this year, when the US plans to begin deployment in Western Europe of 572 Pershing II and ground-launched cruise missiles. But the administration must move promptly.

The issue is a simple one. East and West confront a substantial imbalance in theater nuclear missiles targeted on Europe. This disparity - important for political, but not for military, reasons - has been worsening since 1977, when the Soviets began replacing older medium-range single-warhead missiles with the SS-20 multiple-warhead missile.

There are two ways to end this imbalance: One is through substantial reductions in Soviet missiles; the other is through substantial increases in US missiles. The first way will - if the Soviets agree - result in fewer nuclear weapons and set a historic precedent. The second way will result in more nuclear weapons and reflect mankind's inability to limit its capacity for mass annihilation.

The choice between the two courses is self-evident. Yet the US is about to decide on the second course - more American missiles rather than fewer Soviet missiles.

This will be the wrong choice. The political cost will be high, spreading doubt and division in Western Europe - and especially in West Germany, where the conservative leadership would welcome an alternative course. The military cost will be high, spending defense funds on nuclear weapons instead of on conventional capability, where it is most needed. More nuclear weapons serve no military purpose: Their use to defend Western Europe would ensure its destruction. The cost in terms of relations with the Soviet Union, approaching a precarious and dangerous state now, will be high. Soviet leader Yuri Andropov has repeatedly warned that the Soviet Union will match American deployment with ''analogous'' deployments of its own. Finally, this move will accelerate the nuclear arms race and make the world less secure.

Why has the US chosen this course? Proponents in the administration say that more American weapons are essential to ''offset'' the Soviet SS-20s and to ensure that the theater deterrent in Europe is coupled with the US strategic deterrent.

As Richard Burt, assistant secretary of state for Europe, implies, more nuclear weapons are not needed for deterrence. In April 1983, he wrote, ''The deployment of 572 new American missiles in Western Europe capable of reaching only limited areas of the Soviet Union has little impact on the US-Soviet balance at a time when both sides have over 10,000 warheads, deliverable on short notice, to any location in the other's country.''

The defense of the US and Western Europe is already coupled through treaty commitment, through the experience of two world wars, and through the presence in Western Europe of 300,000 American troops. NATO already possesses a formidable American nuclear missile force with medium-range capability: 400 Poseidon warheads assigned to the NATO commander and an integral part of the deterrent in Europe. In the current debate about more missiles for Western Europe, the administration has remained silent about these powerful, sea-based Poseidon missiles. Yet these sea-based warheads are invulnerable and, therefore, more stabilizing. On the other hand, the land-based missiles the administration proposes to deploy are vulnerable, less stabilizing, and located in densely populated areas of Western Europe.

Instead of deploying these weapons, the US should propose reductions to the Soviet Union. The purpose of a reduction agreement would be defined as the restoration of the overall warhead balance on medium-range missiles that existed prior to 1977. The Soviet Union would dismantle missiles carrying about 700 warheads, leaving about 600, the number deployed before 1977. And the US would cancel the deployment of the 572 Pershing II and ground-launched cruise missiles , which can strike the Soviet Union. The US has had no missiles with this capability in Western Europe for 20 years.

This agreement would meet the contradictory positions of both the US and the Soviet Union on the issue of British and French forces. These forces would not be taken into account in calculating reductions, thus meeting the US position. On the other hand, if Moscow retained 300 warheads targeted on Europe and 300 targeted on Asia, the outcome from the Soviet point of view would be the same as if the reductions were based on the British and French level. This would meet the Soviet position.

The political effects of this proposal, involving the destruction of over half the Soviet missile force, would be far-reaching. Britain and France might then defer plans to expand their forces, obviating the need for further negotiations. The US and the Soviet Union would have turned away from confrontation and introduced a measure of sanity into their relationship.