Still needed: a strategic arms control proposal

President Reagan is being praised for ''flexibility'' in modifying US positions in the strategic arms talks with the Soviet Union. Many hope that the President's June 8 announcement significantly increases the prospects for a concrete arms control agreement with the Soviet Union.

Unfortunately, the President's announcement appears to constitute mainly tinkering with some of the numbers in the existing American START proposals. There will not be a real prospect for agreement until the United States thinks through, and adopts, an integrated set of practical goals. The US needs a coherent policy which interrelates all key elements - feasible reductions, balanced restraints, workable verification, and a long-range negotiating framework.

''Flexibility,'' by itself, and tinkering with a few numerical limits, will not fill the bill. The value of flexibility obviously depends on the nature of the changes that have been made - and those that have not been made.

Reagan makes much of his decision to relax an American proposed limit for each side of 850 deployed ballistic missiles. This decision is supposed to reflect a shift in emphasis toward limiting warheads rather than missiles. This change is also designed to permit, in 10 or 20 years, a large number of the small American missile known as Midgetman.

However, the American START proposal contains many other numerical limits, some specifically on numbers of warheads, and there is no indication that they have been changed.

The US has proposed, for example, that each side limit the number of warheads on its land-based ballistic missiles to 2,500. The Soviet Union now has about 6, 000. It has therefore been asked to undertake a reduction of approximately 60 percent. The US, on the other hand, now possesses only 2,100 such warheads. Consequently, it could increase its arsenal of such warheads by about 20 percent. These figures, incidentally, pertain to the area of weaponry which the Reagan administration has declared to be most dangerous and destabilizing - at least when possessed by the Soviet Union - land-based, highly accurate, multiple-warhead missiles.

It takes little political savvy to see that a proposal such as this one is likely to be accepted by the Soviet Union, to use Khrushchev's famous phrase, ''when shrimps learn to whistle.''

Moreover, the President has not indicated any change in some other limits specifically pertaining to Soviet missiles. The US position also called for a reduction of over two-thirds in the number of SS-17s, 18s, and 19s - the largest and most modern Soviet missiles which together carry about three-quarters of the total Soviet land-based warheads. These proposals also are nonnegotiable.

Of course, all of these numbers could become the subject of further tinkering. But they were put forward in the first place as a reflection of an impossible objective - to bring about a revolutionary transformation in Soviet forces. Moscow was to be ''permitted'' to strengthen its submarine launched forces, at gigantic expense, while being required to carry out cuts of roughly two-thirds in its heavy land-based missiles.

Accordingly, a new, much more gradual and balanced set of negotiating goals is called for from the US. Many different sets of numbers or percentages might be practical and worthwhile once it is accepted that the US cannot achieve, by negotiation, the decimation of the Soviet ICBM force.

Unfortunately, statements of worthy generalities, like the desire for ''significant reductions'' or ''enhanced stability,'' are not a substitute for specific goals based, not only on our own desires, but also on the realities of Soviet history and geography.

The Scowcroft Commission's report on strategic arms control calls repeatedly for ''evolution'' and a ''long-term'' approach to the restructuring of strategic forces. Decades are envisioned for the restructuring of American forces. Why shouldn't decades also be envisioned for the restructuring of Soviet forces? Specific American arms control goals will either reflect this basic requirement, or they will be essentially propagandistic and irrelevant as guidelines for achievement.

Formulation of coherent US goals must also include realistic calculation of what the US is prepared to offer that will be of value to the Soviet Union. Moscow will be reluctant to agree even to a gradual reduction and restructuring of its most highly valued forces unless the US is ready to limit significantly some of its new systems which Moscow finds threatening. Yet there is no indication of a US arms control policy that offers to cut back on existing American plans for new cruise missiles, new counterforce weapons like the MX and the D-5 missile for the Trident, or new B-1 bombers.

Effective and practical verification also needs to be a part of an integrated policy. However, the administration has yet to formulate concrete requirements. It has proposed limitation in the number of Soviet missiles whether or not deployed on launchers - that is, wherever they may be stored. This objective, the need for which is debatable, would require extraordinarily intrusive verification. But no specific verification procedures to carry it out have reportedly been offered by the US.

Finally, and above all, arms control goals must be formulated within the framework of a continuing long-term process. The reason is simple. Total and perfect solutions will never be achievable in any one agreement - not by Reagan or any other American president. This is especially so when current strategic arms control goals, to be at all realistic, must contemplate a gradual evolution of both Soviet and American forces.

But imperfect and gradual steps become politically tolerable if it is understood that they are part of a continuing process. Further improvements, after all, can be made in subsequent negotiations.

This approach does not mean that gradual arms control steps must be of negligible value. An agreement which reduces and limits Soviet missile warheads enough to ensure the continued survivability of US forces would be of very great intrinsic value. And current strategic realities do not require more for American security.

Arms control may be compared to a bicycle. It will stay up as long as it is moving forward. The task that now confronts the US is clear - to formulate a realistic arms control policy of gradual steps that will get the arms control bicycle moving once again.