`Star wars' remains key issue in arms talks. It is not only point of dispute but is so central only US, Soviet leaders could resolve the impasse

Despite November's Soviet-American summit, the superpowers resumed arms control talks here much the way they left off last year. The summit made it harder for the two sides to call each other names, but did little to move concrete offers forward. At their meeting in Geneva, President Reagan and Communist Party General Secretary Mikhail Gorbachev did agree to ``accelerate'' the negotiations. And both sides accentuated the positive at the opening session of Round 4 Thursday.

Soviet chief negotiator Viktor Karpov told reporters he would be formally presenting Mr. Gorbachev's proposal made Wednesday to banish all nuclear weapons by the year 2000. And he repeated Gorbachev's suggestion at the summit that an interim agreement on intermediate-range nuclear weapons in Europe might be possible without any direct link to other nuclear arms control talks.

His American counterpart, Max Kampelman, stressed that ``the American delegation is here in a constructive spirit, anxious to find accommodations.'' And even President Reagan avoided his more usual branding of Soviet proposals as propaganda and noted that Gorbachev's latest offer has certain elements that may be constructive.

Yet it is notoriously hard to translate into a treaty this common desire to banish nuclear weapons in the future and halve offensive strategic arsenals. Indications are that Gorbachev made it even harder by two crucial omissions at the summit.

Both omissions concern the key issue of the Strategic Defense Initiative (SDI, or ``star wars''), Reagan's space-based defense research program. This is the United States military program that most worries Moscow -- and that the Kremlin insists must be curtailed before it will agree to any deep offensive cuts at all.

The first omission, according to sources familiar with the summit exchanges, was Gorbachev's failure -- despite repeated Soviet public musings to the contrary -- to modify Moscow's unrealistic demand that all SDI efforts be banned, including even unverifiable laboratory research. In a presummit interview with Time magazine, Gorbachev indicated more flexibility in distinguishing between allowing unverifiable basic research and outlawing verifiable testing in space. But the official Soviet position never budged, either in Round 3 or at the summit.

Gorbachev's second omission was not to insist that the well-known Soviet concern about SDI appear explicitly in the final summit communiqu'e.

The combination of these two omissions left US hawks jubilant after the summit -- and weakened those moderates within the Reagan administration who most want to reach an arms control agreement. The hawks have been arguing ever since that if only the US hangs tough on SDI, Moscow will eventually give up and concede the point. The fledgling Gorbachev needed a summit success more than Reagan did, they reason, and therefore the Soviet leader could be stonewalled into dropping his public demands on SDI in order to get a joint communiqu'e. Similarly, Gorbachev needs the financial respite of arms control more than the US does. If the US stands firm in refusing to yield on SDI, the thinking goes, Moscow will eventually cave in on the substance as well as the formal statement.

Since the summit, Soviet spokesmen have vigorously contested this interpretation. And US hawks would lose no sleep if the Soviets did reject any offensive arms limits because of an impasse over SDI. But the failure even to explore opening SDI positions greatly reduces the room for maneuver of the administration moderates.

The obverse side of the US hawks' jubilation since the summit is therefore the moderates' disarray. The provisional ascendancy of moderates within the Reagan administration in the two weeks preceding the summit was premised largely on the desire of Nancy Reagan and Chief of Staff Donald Regan to secure the President's place in history as a peacemaker as well as an arms builder. Notably, in that fortnight, Reagan spoke only of the non-negotiability of SDI and SDI research in general -- not of the non-negotiability of SDI testing. Yet once Gorbachev failed to probe this restraint or exhibit flexibility of his own, the incentive was gone for Reagan to hold back. Immediately after returning to Washington Reagan again said that SDI testing is non-negotiable.

SDI is not the sole barrier to arms control now -- but it is the most formidable. So central is it that only the top leaders themselves could begin to resolve the impasse.

Nor will they have in this January-February round the pressure for progress generated by an impending summit. Last fall the forthcoming summit concentrated minds sufficiently to produce both the first comprehensive Soviet proposal since talks began a year ago and the US counterproposal. Such pressure might again have been generated for Round 5.

With the next summit postponed until the fall or even December, however, the pressure is off the Geneva negotiators. Observers therefore expect little except marginal probes during the next two months. Third of three articles on the resumption of arms control talks. Previous articles appeared Jan. 15 and 16.