The abrupt resignation of Soviet Foreign Minister Eduard Shevardnadze threatens to slow the rapid pace of U.S.-Soviet cooperation on a broad agenda of unfinished business ranging from the Persian Gulf to arms control, and exposes a worrisome new depth to the Soviet leadership crisis, U.S. officials said yesterday.

These officials, and a number of outside experts, predicted that Soviet President Mikhail Gorbachev still has strong reasons to continue his accommodation with the West, if only to prop up his collapsing economy. But some expressed concern that the resignation could be at least a symbolic setback to the solidarity of the international coalition seeking to expel Iraq from Kuwait, in which Shevardnadze played a prominent role.

They also described Shevardnadze's sudden departure, further weakening Gorbachev, his friend of 20 years, as a startling revelation of the extent of the internal Soviet split between reactionaries who want a more authoritarian central regime and radical reformers who want to break up the union.

Secretary of State James A. Baker III, who forged a close working relationship with Shevardnadze over the past two years, said the Soviet minister's anguished cry that "we are heading towards a dictatorship" had to be "taken seriously." Baker cautioned that "our new relationship with the Soviet Union depends on its continuing commitment to democratization and reform."

Many U.S. analysts said they fear the resignation was really a warning from Shevardnadze that the promising aspects of the Gorbachev era could be coming to an end.

"The Soviet Union cannot afford to have worse relations with the United States and the West in general," said Adam B. Ulam, professor of history and fellow at Harvard's Russian Research Center. "But internal pressures may compel Gorbachev to take actions which may alienate many people in the West. Shevardnadze's resignation is an acknowledgement that Gorbachev may have to resort to these measures and he doesn't want to go that far. This puts Gorbachev in an even weaker position than he was before."

Soon after Shevardnadze's announcement, the CIA sent to policy-makers a list of a dozen possible successors, including Yevgeny Primakov, another Gorbachev adviser with long experience in the Middle East, and the Soviet ambassador to Washington, Alexander Bessmertnykh. While analysts said there remains much uncertainty about who will fill Shevardnadze's post, they suggested that the shift inevitably will bring a pause in what had been accelerated cooperation between Washington and Moscow.

In particular, the resignation could complicate the U.S. effort to convince Saddam Hussein that the global coalition will force him to withdraw from Kuwait. Gorbachev pledged after the resignation that Soviet foreign policy would not change, and Baker said he was "absolutely, totally and completely" certain that the departure would not impair the gulf effort.

At the same time, Baker acknowledged that the gulf was one area where Shevardnadze's personal role in Soviet decision-making had been decisive.

Michael Mandelbaum of the Council on Foreign Relations said, "No one who succeeds him is likely to be as committed to a pro-American, pro-western policy as Shevardnadze was. Even if the policies remain the same, they are not likely to be pursued with the same enthusiasm and, even if the words are the same, the music will be different."

It was the gulf crisis that prompted much of the internal Soviet criticism of Shevardnadze that led to his emotional farewell statement to the Congress of People's Deputies. In his address to the U.N. General Assembly in September, Shevardnadze had declared that the Security Council could -- and would -- use force to expel Iraq from Kuwait if necessary. He returned to Moscow to face hostile questioning in the Supreme Soviet, and criticism from the military and others that intensified and finally "exhausted my patience," as he put it yesterday.

The same sentiments will confront the new foreign minister. In addition, if Gorbachev selects Primakov, he could be signaling a shift in approach to Saddam. Primakov has known the Iraqi leader for many years, and said after visiting him twice in October that Saddam needed to be shown a face-saving way out of the gulf crisis. That approach is at odds with the determination of the anti-Iraq coalition to make no concessions, and analysts said there is a danger that Saddam could take Shevardnadze's departure as a sign that one of his worst critics has fallen away.

But senior policy-makers also said they believe that Shevardnadze's approach to the gulf was fully backed by Gorbachev, and that the Soviet leader would continue to pressure Saddam. One official noted that the Soviet Union still has been unable to extricate its citizens from Iraq. Baker noted that Gorbachev had spoken harshly to Iraqi Foreign Minister Tariq Aziz last month over the issue.

A second official said of the gulf crisis, "Gorbachev knows it is extremely important to us. He wants our help." This official recalled how Gorbachev had pledged his cooperation to Baker at a meeting last month in Moscow. "I would be dubious that on an issue that is that prominent that he would now move away from it."

The Shevardnadze resignation could also stall completion of other items on the U.S.-Soviet agenda. Sen. Joseph R. Biden Jr. (D-Del.), chairman of the Senate Foreign Relations subcommittee on European affairs, said Shevardnadze's departure could threaten "many of the tentative agreements" reached with Baker in recent months.

Among them is START, the strategic arms reduction treaty, in which both sides are still involved in end-game negotiations over technical details. Shevardnadze had repeatedly taken the offensive against the Soviet military, pushing them for concessions on everything from Eastern Europe to arms control.

But new sympathy that Gorbachev has begun to show for military complaints in general could make completion of the treaty -- scheduled for signing at a planned February summit in Moscow -- more difficult.

Among the pieces of business left unresolved with Shevardnadze's resignation, U.S. officials said, is concern about the extent of Soviet compliance with the recently completed treaty on conventional arms in Europe, and ongoing questions about the veracity of weapon counts provided by the Soviet military.

Shevardnadze also left behind incomplete negotiations with Baker over settling civil wars in Afghanistan, Angola and Cambodia.