WASHINGTON -- Faced with a new NATO ultimatum to silence their guns or face immediate air attack, the Bosnian Serbs agreed last night to a cease-fire around Gorazde, starting today.
With more than 100 alliance warplanes -- more than half of them U.S. attack jets -- now on hair-trigger to quell any further Serbian shelling of the beleaguered Muslim enclave or five other U.N.-declared "safe areas," President Clinton told reporters, "The Bosnian Serbs should not doubt NATO's willingness to act."
As night fell in the isolated city, where more than 500 people have died in the three-week siege, Yasushi Akashi, the senior United Nations official in the former Yugoslavia, said the cease-fire would take effect today at 4 a.m. EDT.
It is the latest in a series of Serbian cease-fires, which usually have been quickly broken. "Frankly, it will be more impressive if we see them begin to move, to withdraw," an administration official said.
Throughout the day, even as NATO ambassadors met to thrash out their threat of expanded air strikes, the Serbs continued their deadly onslaught on Gorazde, according to U.N. relief workers.
The NATO decision, a major escalation of the 16-nation alliance's military involvement in the civil war, followed a request by U.N. Secretary-General Boutros Boutros-Ghali and Mr. Clinton for wider use of air power to protect the six "safe areas."
A similar threat of alliance air strikes in February ended the siege of Sarajevo, with Serbian forces withdrawing or handing over their weapons to U.N. control without any attack being necessary.
Sitting as the North Atlantic Council in Brussels, Belgium, the NATO ambassadors placed these demands on the Serbs:
* Immediate cease-fire around Gorazde, under threat of instant attack on any forces that open fire.
* Withdrawal of forces 2 miles from the center of Gorazde by 8:01 p.m. EDT today. Failure to comply would unleash NATO attacks on any military targets within 12 miles of town.
* Free movement of U.N. peacekeepers and humanitarian aid workers in and out of Gorazde, where medical services have been all but destroyed by Serbian shells.
* Refrain from attacking the five other exclusion zones -- Sarajevo, Srebrenica, Tuzla, Bihac and Zepa -- or face air strikes.
"The situation demands action," NATO Secretary-General Manfred Woerner said at a news conference. "The murderous, barbarous attacks against defenseless civilians are an outrage. It is now up to the Bosnian Serbs to heed these demands or they will face the most serious consequences."
While throwing his support behind the latest initiative, Mr. Clinton again stressed that he was not ready to commit U.S. ground troops.
"When the United States goes into a situation like this, I think it fundamentally changes the character and nature of the engagement," he said. He repeated his offer to contribute troops to a U.N. peacekeeping mission only after a settlement.
"We don't want to create the impression that the United States or the U.N. is entering the conflict to try to win a military victory on the ground," he said.
He intends to create, he said, "the clear and unambiguous impression" that he and the allies were "angry and disappointed" at the Serbs' continuing aggression and refusal to return to negotiations.
NATO's three objectives, Mr. Clinton said, are:
* To "reverse the terrible things" happening in Gorazde.
* To make the six "safe areas" actually safe.
* To use "firm resoluteness" to get the warring parties back to the negotiating table.
He said he was discussing diplomatic moves with the Russians, who were "angry and frustrated" over being misled over Serbian intentions to cease their aggression but have withheld approval of allied air strikes, and he expected progress next week.
The next diplomatic move could come in London on Monday, when U.S. Secretary of State Warren M. Christopher is to meet British Foreign Secretary Douglas Hurd.
A State Department official said that depending on events in Bosnia over the weekend, Russian Foreign Minister Andrei V. Kozyrev and France's Alain Juppe might be invited to join the session .