The US and USSR: forging a workable arms package. A mutually beneficial agreement is still possible in the new year

DESPITE the impasse that developed at Reykjavik over reaching an arms control agreement, both United States and Soviet officials have said that negotiations should continue. Serious obstacles remain. Recent conversations with Soviet officials and academicians, however, lead me to believe that the Soviet Union is prepared to alter its position on several crucial issues that might bring the sum of them closer to what the Reagan administration says would be acceptable for consideration. Even so, new roadblocks may prolong the negotiations and make an agreement difficult to reach.

The Soviets insist the proposals they brought to Reykjavik must be taken as a package: offensive, defensive, and intermediate-range nuclear weapons.

The problem with a package deal is that, like a Rubik's cube, if any piece doesn't fit or falls out, the puzzle cannot be solved. On the other hand, a package covering multiple weapon systems offers the opportunity to strike bargains across different subject areas, and that may make compromise easier.

How does the package now look?

Offensive forces. Both sides are standing firm in favor of 50 percent reductions in strategic offensive forces within a five-year period. The US has asked for subceilings on Soviet heavy land-based ICBMs (the SS-18s and 19s) in order to remove what is perceived to be the most serious threat to the US deterrent force. The Soviets had earlier proposed a 60 percent limit on force concentration of any type of system, which would have had the effect of imposing a subceiling on their heaviest missiles. At Reykjavik, they refused any subceilings, insisting on across-the-board cuts of 50 percent, to specifically include 50 percent cuts in the SS-18s. Since that time there have been indications that a position could be worked out to meet US concerns.

A second potential obstacle raised by the Soviets is modernization. The proposal for 50 percent reduction of strategic offensive forces was couched in terms of warheads and launchers. It did not contain restrictions on system substitution. The Soviets have stated that some restriction on modernization is necessary to prevent growth of capability in the permitted forces, circumventing the limits established by agreement. The US will resist such restrictions. But since offensive ballistic missiles are close to technological maturity anyway, and since Congress has shown little enthusiasm for new ICBM programs for the past 10 years, a compromise on modernization should be possible.

The Soviets proposed to eliminate long-range nuclear weapons in the second five years. President Reagan proposed the elimination of long-range ballistic missiles only. Despite contradictory accounts, it appears that he initially agreed to the Soviet position. Both sides have retreated. After widespread expression of consternation in the alliance, and intense pressure from Prime Minister Thatcher, the President backed away even from his own proposal to eliminate ballistic missiles, and has ignored the more sweeping proposal for abolition. Soviet officials and academicians, in conferences and private talks, seem to accept a more modest goal for the second five years: perhaps half again of the 50 percent that remains after the first five years. They do not abandon Mikhail Gorbachev's ultimate goal of eliminating nuclear weapons, but recognize that for a nuclear-free world to be safe, the agreement must be international, not bilateral, and that before such a regime can be seriously negotiated, political conditions must change. Thus it may be said that the Soviet second-stage proposal is not an essential precondition to the initial 50 percent reduction of strategic offensive forces.

While a comprehensive test ban treaty is a high Soviet priority, it does not appear to be a condition to offensive arms cuts, if substantial progress is made.

Intermediate-range nuclear forces. The proposal that both parties reduce intermediate-range nuclear forces (INF) in Europe, Asia, and the US was accepted by both sides in Reykjavik. It probably remains firm, despite alliance concerns.

German officials admit that the two-track decision adopted by NATO in 1979 contemplated that arms control might eliminate the Soviet SS-20s and the asserted need for US deployments. But now that Pershing 2's and ground launch cruise missiles (GLCMs) are in place, many Europeans regard them as additional tangible evidence of US commitment to defend Europe. Their removal, it is argued, would weaken that commitment. It is unlikely, however, that the Europeans will resist the basic INF agreement in the long run, although they may try to attach conditions that delay and complicate it.

Further, while both parties agree that a vigorous effort for conventional arms reduction is necessary and negotiations should begin, they will be extremely complex. Talks on balanced cuts in forces have been in session for 13 years, with little tangible result. The time may be ripe for progress, but a linkage to INF would involve extensive delays.

The administration would like to separate the Soviets' new INF proposal, where they have made many concessions, from the rest of the tripartite package. The Soviets, however, can be expected, as a matter of political leverage, to continue to refuse to do so for the time being.

Defensive forces. The Soviets' Reykjavik proposal stated:

``For the purposes of strengthening the ABM Treaty of 1972 of unlimited duration, agreement should be reached about the USSR-USA commitment not to withdraw from the treaty for 10 years, and they should strongly meet all obligations in their entirety.

``Testing of all space-based elements of ballistic missiles defense in outer space, except research and testing in laboratories, should be prohibited....''

The proposal was viewed by the US delegation as calling for change in the ABM Treaty and rejected out of hand by the President. The last sentence quoted does not seem to make sense, and the US delegation apparently did not ask for an explanation. Since that time, Soviets have stated unofficially that the sentence was the product of an internal bureaucratic compromise, and in fact can be read to include testing in space-based labs.

I have pointed out to various Soviet officials that their Reykjavik position appears more restrictive than the ABM Treaty. The treaty, in its historic or strict interpretation, prohibits testing of components (undefined in the treaty) of space-based defensive systems, but does not prohibit testing of technology or something less than components. I was told the Soviets would now be satisfied by a 10-year commitment not to exercise the right to withdraw from the ABM Treaty as it stands.

The real gulf between the US and the USSR is not whether testing is to be confined to the laboratory, but a chasm in the interpretation of the ABM Treaty. Article V of the treaty prohibits testing and development of space-based systems. The administration, however, has advanced a new interpretation that would permit testing and development of space-based systems contemplated by Strategic Defense Initiative (SDI). It argues that these are not ABM systems covered by the treaty. Therefore, while it seemed as though both parties were prepared to accept a 10-year commitment not to withdraw, their positions on what the treaty permits and prohibits remains worlds apart.

Yet the state of technology and the advances made in the SDI program are such that it would probably not be possible to test space-based components during the Reagan administration or for several years thereafter. Indeed, experts maintain that a sensibly paced research program would not bump into treaty restrictions for 10 years. So agreement along the lines of the Soviet proposal could be accepted without abandoning the goal of a defensive shield.

It will take the highest skill and commitment to conclude a treaty based on the key elements of the Reykjavik package. It will involve expert management of both internal domestic and alliance factions. It is not clear that the administration could overcome the obstacles even with the strongest commitment, given the paralysis that the Iran-Nicaragua investigations are likely to cause in the coming months. But the Reykjavik proposals and their most recent elaborations have set the agenda for serious arms control for the foreseeable future. They deserve professional and public discussion.

Antonia Handler Chayes is chairman of Endispute Inc., a dispute resolution firm, and former undersecretary of the US Air Force.