After 78 days of NATO bombing, Yugoslav military commanders signed an agreement tonight to withdraw their forces from Kosovo beginning Thursday, making way for the entry of U.S. and allied peacekeeping troops and the return home of more than a million ethnic Albanians. NATO officials said the bombing would be suspended as soon as they can verify that a pullout has begun.

The agreement reached here tonight between Yugoslav and NATO military commanders came after five days of fitful haggling over the details and timing of the Yugoslav pullout and the deployment of the peacekeepers. Its completion also sets in motion other political and military measures meant to restore peace and stability in Kosovo, scene of a fierce assault by Yugoslav troops and Serbian police on ethnic Albanian separatist rebels and civilians.

British Lt. Gen. Mike Jackson, the NATO commander who will lead the stabilization force in Kosovo and the alliance's chief representative here, said the accord "details how the army, the interior police and all other forces should conduct a phased, verifiable, and orderly withdrawal from Kosovo." It requires an estimated 40,000 heavily armed men -- who have spent most of the past two months digging in for a long stay -- to withdraw within 11 days.

The agreement also sanctions the entrance into Kosovo of a NATO peacekeeping force of more than 50,000 troops, which the Serb-led Belgrade government had said it would never permit. The first troops, most likely British de-mining units, will likely begin to deploy in Kosovo in the next day or two.

[In Brussels, ambassadors from NATO's 19 nations quickly approved the "military technical agreement" worked out by Jackson in Macedonia. In a declaration issued shortly after 1 a.m. Thursday at NATO headquarters, Secretary General Javier Solana hailed the accord as "a great day for the cause of justice and the people of Kosovo." He added: "We are ready to suspend air operations once we have verified the effective beginnings of the withdrawal of Yugoslav forces."]

In Washington, President Clinton was less effusive in his reaction, calling the agreement "another important step toward achieving our objectives in Kosovo." He added: "We and our allies will watch carefully to see whether the Serb forces are peacefully leaving Kosovo in accordance with the agreed timetable."

Defense Secretary William S. Cohen remained vague on how extensive a Yugoslav withdrawal would have to be before NATO formally suspends the airstrikes. "We will know it as such when we see it," Cohen told reporters in Washington.

But other U.S. defense officials indicated the order to halt the air campaign would likely come after daylight Thursday, once Gen. Wesley K. Clark, NATO's supreme commander, can verify that Yugoslav forces have started moving out of northern Kosovo in the first phase of the carefully choreographed pullout.

Under the agreement, the suspension of airstrikes is to be followed by a U.N. Security Council resolution authorizing deployment of the peacekeeping force -- a provision aimed at placating Yugoslav authorities and their Russian advocates, who objected to a purely NATO intervention in Kosovo.

In New York, the 15-nation Security Council waited all day for NATO headquarters to signal that it could vote on a resolution authorizing the peacekeeping force. This evening, the council finally broke off consultations but was expected to reconvene Thursday.

Under the agreement, more than 800,000 ethnic Albanian refugees forcibly expelled from Kosovo will be entitled to return, probably beginning in a month or so. U.S. and NATO officials have said Belgrade will have no role in deciding which refugees will be allowed to return. Another 500,000 ethnic Albanians are believed to have been driven from their homes but remain in Kosovo.

While eager to see most of the refugees return to their homes before winter, U.S. and allied officials are worried about a potential stampede back to Kosovo, a province of Serbia, Yugoslavia's dominant republic. Pentagon officials said no effort would be made to prevent refugees from going back, but Cohen made it clear that an attempt would be made to persuade as many as possible to wait until towns and roads are cleared of mines and made safe for their return.

"We can't put any specific time frame on this," Cohen said. "We hope to get them back as quickly as we can, but as safely as we can. And so safety will be the primary driving factor here."

The accord, signed in a portable hanger at a NATO helicopter airfield five miles south of the Yugoslav border, appeared to signal the conclusion to an air campaign that had sorely tested the political resolve of the world's most powerful and technologically sophisticated military alliance.

The conflict also produced war crimes indictments against Yugoslav President Slobodan Milosevic and other leaders for their role in the brutal purging of Kosovo's ethnic Albanian majority, a scorched-earth campaign that shocked much of the world and sharpened Western calls for Milosevic's removal.

"It has not been easy going," Jackson said in a terse but upbeat statement 85 minutes after the two delegations began their final meeting. He emphasized that reaching agreement was complicated "not least because there has inevitably been a political as well as a military dimension" required to achieve success.

The agreement was confirmed here by Gen. Svetozar Marjanovic, the Yugoslav army's deputy chief of staff and the Belgrade government's chief representative. "The negotiations were very difficult, but finally we managed to sign the agreement," he said. "It means that the war ended. It also means that the policy of peace prevailed. . . . We showed that we are really for peace." As Marjanovic spoke, Jackson strode to his waiting helicopter and ordered the engines powered up.

The first NATO troops to deploy in Kosovo -- well before all Yugoslav forces will have withdrawn -- will be a team of British demolition and land mine experts, members of the famed Gurkha unit of the Fifth Airborne Brigade. Their task will be to help clear explosives placed by Yugoslav troops on a dozen or so bridges and tunnels along the road north of the Blace, Macedonia, border crossing. The explosives were intended to block a NATO ground offensive that never came.

At the same time, NATO helicopters will ferry troops to peaks in the Crna Gora mountains overlooking this road; once it is secured, Jackson will drive 50 miles north in a convoy of German, French, Italian and U.S. troops and armored vehicles to reach Pristina, the Kosovo capital, where he will establish his headquarters near the airport. This process, one official said, might take just one day.

[Early Thursday, the Pentagon reported that 1,900 Marines who had been waiting aboard three ships off Greece landed on the beach of Litohoro and prepared to head to Macedonia, the principal staging area for the peacekeeping mission. U.S. Army units from Germany and Albania also were to start converging on Macedonia.]

"It is tragic that intransigence has made it necessary . . . to resort to airstrikes," Jackson said after the agreement was signed. He added, however, that "now is the time to look ahead" and that the agreement "represents the hope of a better future in which we can rebuild Kosovo and restore some normality to the lives of its ordinary citizens."

U.S. and NATO officials said one key aspect of the peacekeeping force remains unresolved -- whether and how Russian troops will participate alongside NATO troops, which are to be under unified alliance command. Deputy Secretary of State Strobe Talbott will discuss the issue in Moscow on Thursday.

Under tonight's agreement, Yugoslav forces are to begin withdrawing Thursday from the northern portion of Kosovo, a step that -- once verified -- will trigger suspension of the NATO air offensive. The withdrawal along specified routes will proceed in phases, with Yugoslav forces departing the southern portion of the province within six days and the central portion within nine. The province is to be emptied of all Yugoslav and Serbian forces within 11 days.

The 11-day deadline represents a concession by NATO officials, who had initially demanded a seven-day pullout. European diplomats said the staging was crafted to prevent any buildup of government forces along the border in numbers great enough to mount a surprise attack against incoming NATO troops.

Other provisions of the draft military accord were altered at Belgrade's request, despite repeated claims by NATO officials that the purpose of the meetings here was to deliver nonnegotiable terms for the withdrawal. In particular, a sentence describing the linkage between the pullout, the bombing halt and a U.N. Security Council resolution was deleted from the draft because, in the words of a State Department official, it "appeared to us, upon reflection, that . . . [it] was unnecessary."

The deletion was approved by NATO foreign ministers at a meeting in Cologne, Germany, late today, and the gesture played a key role in persuading Yugoslav officials who had left the talks to return here for the final session.

By accepting an 11-day deadline for the pullout, NATO essentially allowed Belgrade to have as much time as its negotiators had sought -- 15 days from last Saturday. In fact, several NATO officials said on Wednesday afternoon that Belgrade's representatives essentially were stalling -- a view based on 10 hours of haggling by the Yugoslav military in the middle of the night over what one NATO official described as "minutiae . . . a word here, a word there, but nothing of substance."

While the talks were underway, Yugoslav security forces had mounted a new offensive against ethnic Albanian separatist rebels around Mount Pastrik near the Albanian border and in an area around the town of Junik. But the offensive was halted Monday when a pair of U.S. B-52 bombers conducted a devastating daylight raid that virtually destroyed two Yugoslav army battalions confronting the rebels.

Yugoslav security forces also used the extra time to conduct additional house burnings and lootings in the southern Kosovo city of Prizren and in central Kosovo, according to NATO intelligence officials. Today, they reportedly were stripping doors and window frames from buildings in Pristina and packing them into trucks and cars.

But the Yugoslav military also suffered major losses because NATO made increasingly effective airstrikes during the talks as a way to pressure the Belgrade government to give way. The alliance's four-day tally of destruction this morning included 29 tanks, 93 armored personnel carriers, 220 field or air defense artillery pieces, 86 mortars and three of the Yugoslav air force's best MiG fighters.

Staff writers Steven Mufson in Cologne, Dana Priest and Bradley Graham in Washington and correspondents William Drozdiak in Brussels and David Hoffman in Moscow contributed to this report.

CAPTION: TIMETABLE TOWARD PEACE (This graphic was not available)

CAPTION: British Lt. Gen. Mike Jackson, left, lead negotiator for NATO in the peace talks, briefs reporters as Gen. Svetozar Marjanovic, deputy chief of staff of the Yugoslav army, listens. The men had just signed an accord on Kosovo.

CAPTION: A Yugoslav soldier and his girlfriend kiss in central Novi Sad as people in Yugoslavia's second-largest city celebrate the Kosovo peace accord. The Yugoslav military agreed to begin its withdrawal from the Serbian province Thursday.