U.S. Seeks Wider Cease-Fire After Sarajevo Success : Bosnia: Western allies, Russia to meet in Bonn today on next steps. One option is to threaten NATO strikes on arms of any faction firing on aid convoys, officials say.

The Clinton Administration began moving Monday to maintain the momentum of the successful cease-fire in Bosnia and to broaden the allied peace initiative beyond Sarajevo to other parts of that beleaguered country.

Saying that most of the Bosnian Serb and Muslim artillery either had now been removed from the Sarajevo area or turned over to U.N. forces, the White House announced that representatives of the United States, its West European allies and Russia will meet in Bonn today to consider what to do next.

President Clinton declared the initial phase of the operation, launched by a Feb. 9 NATO threat to bomb any un-monitored Serbian artillery remaining near Sarajevo after early Monday morning, a success. He met briefly with his top national security advisers to review options for expanding the cease-fire around Sarajevo and for speeding the stalled Bosnian peace negotiations.

U.S. officials said the allies were considering expanding the NATO ultimatum by threatening to attack the heavy weapons of any warring faction that tried to fire upon U.N. humanitarian relief convoys elsewhere in Bosnia-Herzegovina.

The Clinton Administration is also backing a peace initiative proposed by the Muslims that would create a combined Muslim-Croatian central government, with additional territory for each of the two factions from land that has been seized by Serbian forces. The new Muslim-Croatian government would ultimately unite with the Serbs in a loose confederation.

“The challenge . . . is to build on this week’s progress and create a lasting and workable peace for all the people of Bosnia,” Clinton told reporters.

The action by the allies came as Sarajevo enjoyed its 10th straight day of freedom from Serbian artillery shelling. Reports from the area said U.N. peacekeeping forces were moving in to take control of the Serbian guns that had not yet been pulled back from the capital or already turned over to the United Nations.

Gen. John M. Shalikashvili, chairman of the Joint Chiefs of Staff, said Serbian commanders had either removed or surrendered to U.N. forces some 250 artillery pieces, tanks and other heavy weapons, by far the bulk of what they had in place. He said Muslim forces, who are opposing the Serbs, had surrendered 46.

As of late Monday, no allied air strikes had been requested to enforce the NATO ultimatum. Allied planes were making runs from Aviano, Italy, and other air bases on Monday, but only to make sure that the NATO order was being observed.

Bosnian President Alija Izetbegovic, a Muslim, said on nationwide television: “Celebrate this victory and don’t be afraid anymore.”

At the same time, U.N. officials reported heavy Serbian shelling of the Bosnian city of Bihac on Monday and artillery attacks on the city of Mostar by Bosnian Croat forces. Neither area is covered by the NATO order.

And Shalikashvili conceded that the allies did not know precisely how many weapons the Serbs actually had in the Sarajevo area because they had not been able to count them, given the snowy weather and large number of hiding places in the region.

“We do not know specifically how many moved, as we did not count every weapon that has been moved out,” he said.

U.S. and allied officials warned the Serbs that the NATO order affecting Sarajevo will continue and that any Serbian unit that brought its weapons back near the city or resumed firing in the area would be subject to NATO air strikes.

“We on the military side are very well aware that this is not the end yet,” Shalikashvili told reporters Monday. He said NATO planes had flown some 150 sorties on Monday alone to make sure that the situation around Sarajevo remained unchanged.

And in Naples, Italy, U.S. Adm. Jeremy Boorda, who commands NATO forces in Southern Europe, pledged that the North Atlantic Treaty Organization would greet any violation of its ultimatum with air strikes.

“Our mission is not over,” Boorda declared. “It is a continuing mission. Any weapons that are not under control will be subject to air strikes. If any weapons are moved back into the exclusion zone they will be subject to air strikes. Anyone who shoots at Sarajevo from anywhere is subject to attack.”

Officials also expressed apprehension about speculation that the Serbs might use some of the artillery they removed from around Sarajevo to shell other Bosnian cities, such as Tuzla and Srebrenica, which continue under siege.

“We’re doing what we can to discourage it,” Clinton said, “and we believe that others will too, including the Russians.” The Russians, who sent 400 troops to Bosnia on Sunday, are traditional allies of the Serbs.

Officials said the meeting in Bonn today is expected to be preliminary, and no major decisions are considered likely. The session has been expanded to include a wide array of officials from key NATO countries, Russia and the U.N. peacekeeping command.

Meanwhile, in a separate development, Haris Silajdzic, the prime minister of the Muslim-led Bosnian government, told U.S. leaders that his country’s major objectives in the talks are to halt Serbian attacks, gain somewhat more territory and rebuild the former Yugoslav republic’s shattered economy.

In a prelude to the Bonn session, Silajdzic met with U.S. Secretary of State Warren Christopher to review options for expanding the peace process and to ask for reconstruction aid from the West.

It was not immediately clear what proposals the allies will pursue next, but there were several on the table.

British Lt. Gen. Michael Rose, the U.N. commander in Bosnia, has proposed using similar NATO ultimatums to clear the heavy weapons from Tuzla and Srebrenica and eventually from the other major Bosnian cities that have been declared U.N.-protected areas.

But the Administration appeared cautious Monday on both possibilities.

Asked about extending the ultimatums to Tuzla and Srebrenica, Shalikashvili warned against NATO’s taking on any more obligations until it is certain that Sarajevo is secure. “This is the time now to consolidate,” he said, “ . . . before we overreach someplace else.”

U.S. officials said, however, that the Administration might consider supporting a proposal to extend the threat of NATO air strikes to cover attacks by any of the three warring parties--the Serbs, the Muslims and the Croats--on U.N. humanitarian relief convoys.

As they have done consistently in recent days, U.S. officials gave most of the credit for this past weekend’s successes to the Clinton Administration and to NATO, mentioning only in passing last week’s Russian initiative that helped persuade the Serbs to surrender their weapons.

Defense Secretary William J. Perry told reporters that the United States had turned down a suggestion by Russian Defense Minister Pavel S. Grachev on Monday that Washington send U.S. troops to help with U.N. peacekeeping operations in Bosnia, saying it would do so only to enforce a peace accord.

Times staff writers Paul Richter in Washington and William D. Montalbano in Naples contributed to this report.