THE MEDITERRANEAN SUMMIT : Soviets Expect Gains on Arms Treaties, Shevardnadze Hints : Diplomacy: Gorbachev apparently has higher hopes than Bush for the results of the conference.

MOSCOW —  Although the meeting of Soviet and American presidents in the Mediterranean will be informal and its agenda open, the Soviet Union nevertheless expects significant progress on arms control and other difficult issues, Foreign Minister Eduard A. Shevardnadze indicated Tuesday.

The Soviet hope, Shevardnadze implied in announcing plans for the meeting, is that President Mikhail S. Gorbachev and President Bush will reach agreement on formulas to resolve the major questions remaining in negotiations on new arms control treaties, which could then be signed next year.

Describing the shipboard meeting as “a major political development,” Shevardnadze said that while the two presidents plan to hold a broad, open-ended dialogue, they will focus on agreements to be concluded at their subsequent meeting in May or June.

“This meeting should be regarded as the most important stage in preparing the negotiations that will take place in the United States during the official state visit there of Mikhail Gorbachev,” Shevardnadze told a press conference.

“But we do not exclude that the leaders will give certain instructions to their foreign ministers and other representatives of our countries so that after this dialogue there will be practical preparations for the Washington summit.”

Boost for Gorbachev

This suggested to Western diplomats that Moscow, as has become customary under Gorbachev, is setting its sights higher for the Mediterranean meeting than Washington is, probably in the hope that this will give the talks greater dynamism and provide the Soviet president with a bit of political leverage.

Since the negotiation of the first strategic arms treaties in the early 1970s, Moscow and Washington have often used summit meetings to reach agreement on broad approaches and occasionally on the resolution of knotty questions in order to move the negotiations forward. The usual device is “agreed instructions,” a term used Tuesday by Shevardnadze.

“Let’s wait and see,” the Soviet foreign minister said when pressed for Moscow’s agenda for the December meeting. “The main thing is that the meeting is to take place.”

Moscow has said repeatedly that it would like to see a preliminary agreement next year on reducing strategic arms by 50%, though serious questions remain open. It also wants agreement on reducing conventional forces in Europe and on outlawing chemical arms, and on protocols that will permit ratification of treaties limiting nuclear tests.

Shevardnadze spoke with evident satisfaction, for Moscow had been attempting for months to engage the Bush Administration in a deeper dialogue but found itself repeatedly put off, first during a “strategic review” and then by evident reluctance of key presidential advisers to commit the United States to negotiations.

Moscow had repeatedly tried to force the pace. Gorbachev went to New York last December to address the United Nations, putting forward new arms reduction proposals then and several times since, with the goal of engaging the Bush Administration.

Shevardnadze, meeting in mid-September with Bush and Secretary of State James A. Baker III, had offered a series of concessions to clear several of the remaining obstacles to the strategic arms reduction treaty, and both sides emerged from those sessions in Washington and Jackson Hole, Wyo., almost rhapsodic about the improved state of relations.

As Gorbachev has continued his meetings with other world leaders the need grew more apparent to officials here for a Soviet-American summit conference.

‘Invited Himself’

“Last year, Gorbachev simply invited himself to the United Nations, and President Reagan and President-elect Bush came up from Washington,” a Soviet foreign affairs specialist commented after Tuesday’s announcement. “But he can’t do that every year.”

Although Bush said in Washington that the meeting was originally his idea and had been accepted by Gorbachev, Soviet officials began searching last summer for a way to bring the two leaders together, believing that a personal relationship would likely develop to strengthen ties between them.

A key consideration for Moscow, Soviet officials said, was the need to allay the concern of many in the Bush Administration, notably Secretary of Defense Dick Cheney and Robert M. Gates, the President’s assistant national security adviser, on the strength of Gorbachev’s domestic position and the durability of his reform program.

“Skeptics are telling Bush that Gorbachev will fail and so why deal with him, why negotiate anything?” a Soviet foreign policy official commented. “This has slowed the negotiations considerably. The prospect of no summit until next summer would have been unacceptable to us without the understanding that there would be the pre-summit meeting now.”

Insight on Tactics

Shevardnadze, questioned about the announcement, provided limited insight into Soviet tactics.

“Both sides found it useful and, I would even say, necessary at this time to hold such an informal, interim summit,” he said. They expected, he said, that the talks would foster “further development and deepening of the positive changes in Soviet-American relations, which have had a positive effect on the world political climate.”

For some here, Shevardnadze’s comments recalled the meeting--also billed as a “pre-summit”--between then President Ronald Reagan and Gorbachev three years ago in Iceland. That session, hurriedly prepared but intended to produce breakthroughs on arms control, collapsed with U.S. and Soviet negotiators at loggerheads over a complex package of interlocking measures.

To keep the meeting in December informal and allow the two presidents and their advisers to get to know one another better, Shevardnadze said, neither side has “set a goal of reaching any agreements on any specific issues,” although the whole range of Soviet and U.S. interests will probably be discussed.