As President Reagan addresses the UN today, American and Soviet diplomats will be working behind the scenes to clear stumbling blocks to a superpower summit. The United States and the Soviet Union appear to be moving closer to a summit meeting, but the case of an American journalist being held in Moscow remains an obstacle.
So does the American decision to single out 25 Soviet diplomats for expulsion from the United Nations in New York.
Two days of negotiations between US Secretary of State George P. Shultz and Soviet Foreign Minister Eduard A. Shevardnadze ended here over the weekend with no definite agreement on a summit, but both sides report progress in clearing away the obstacles to a meeting.
The two men could meet again in New York to continue their discussions, but no definite plans have been made. Meanwhile, talks are proceeding to seek an end to the impasse -- especially since both sides now believe a summit could give substantial impetus to arms control efforts.
Mr. Shultz, speaking Sunday on the ABC-TV program, ``This Week with David Brinkley,'' said a letter delivered to President Reagan from Soviet leader Mikhail Gorbachev contained ``a rather extensive discussion. . . . Most of it was [on] arms control.''
In a press conference on Saturday, Shultz said that the talks here ``have indicated that considerable potential for progress exists. But the cloud that hangs over all this is the fact that Nicholas Daniloff is not free to leave the Soviet Union.''
Shultz said, ``I think it is difficult to think of a fruitful summit without [the Daniloff case] being resolved.''
Mr. Shevardnadze, in a separate press conference, agreed that the discussions here were ``practical and useful.''
But he complained that actions by ``someone's malicious hand'' were aimed at blocking a summit.
``And one of these actions,'' he said, ``is the demand to reduce by 25 persons the staff of the Soviet Mission to the United Nations. This is an unlawful, irresponsible, and provocative decision.''
Despite the continuing disputes over Daniloff and the expulsions, however, there did appear to be some progress on other key issues, particularly prospects for an agreement on intermediate-range nuclear missiles (INF).
``That's perhaps one of the most promising areas,'' said Shultz.
Shevardnadze agreed that ``this work [the talks here in Washington] creates a foundation for holding a productive summit meeting.''
Shevardnadze also acknowledged that the Kremlin had dropped its demand that any INF agreement take into account the planned modernization of the British and French nuclear forces. Moscow had wanted to offset the numbers of US intermediate-range missiles in Europe by taking into account the new British and French forces.
Shevardnadze termed this ``a very serious step of accommodation -- compromise -- in order to rid Europe of the nuclear danger.'' But he said the expulsion of the 25 Soviet diplomats, who have been given until Oct. 1 to leave, will not be ``without consequences.''
Shultz, questioned on the possibility of retaliation by the Soviets, said, ``The President is keeping his powder dry.''
White House officials indicate that the Daniloff case will be mentioned prominently in the President's speech at the UN today. The White House is still pursuing its strategy of demanding that Daniloff be released, but trying to keep arms control negotiations on track. The Soviets are being told privately, however, that the longer Daniloff is held the more complicated that effort becomes.
The Soviets are pressing the US to guarantee not to violate the 1972 Anti-Ballistic Missile treaty for another 15 to 20 years. During that time, both sides would theoretically be able either to reduce their nuclear arsenals to the point where the President's Strategic Defense Initiative became unnecessary or, alternatively, jointly move toward deployment of missile defense systems without destabilizing the nuclear balance.
The US also sees the Stockholm negotiations on confidence-building measures in Europe as another example of East-West seriousness to reach agreement.
Shevardnadze said the Kremlin favors a ``normal resolution'' of the Daniloff case, perhaps suggesting that a trial of the correspondent might be avoided. US diplomats intend to pursue that goal as they continue talking.
But the White House calculation is that if President Reagan appears to be softening on the Daniloff issue, it will send the wrong message to the Kremlin -- and to the American electorate.
Reagan met with Shevardnadze on Friday to convey personally his concern over Daniloff's situation. The Reagan administration hopes that Shevardnadze will convey that concern directly to Gorbachev -- thus speeding the journalist's release.