As British Desert Rat armored personnel carriers clanked into Kosovo today, part of a NATO convoy stretching back 35 miles to the Macedonian border, a group of Yugoslav soldiers in Urosevac watched dejectedly from a gasoline station used as a command post.

Asked how long his troops would remain, Yugoslav Lt. Jozef Feher replied, "This is our country. We'll stay as long as we want."

"We're expecting them all out by 2 p.m. tomorrow -- all 1,000," retorted British Maj. David Rose, after a terse conversation with Feher and other Yugoslav officers.

Despite the heroes' welcome that allied peacekeepers received from ethnic Albanian villagers who clapped, danced and chanted "NATO!" as they passed, the troops who entered Kosovo encountered numerous potential conflicts and risks.

In the provincial capital of Pristina, Yugoslav soldiers and Serbian police were present in many areas, automatic gunfire was heard repeatedly, and ethnic enmities erupted anew.

Some Kosovo Albanians already had started harassing their Serbian neighbors, Rose noted, now that allied tanks and other NATO forces were in full view. "We're trying to sort everything out and get everybody over this difficult period," said Rose.

While the advancing NATO force reported suffering no violence, the perils were evident shortly after the peacekeepers crossed into Kosovo. Yugoslav forces had left behind a mine in a highway tunnel in the Kacanik gorge four miles north of the Macedonian border, which British minesweepers needed more than an hour to clear. There were other, unexplained delays that held up the more than 400 Challenger tanks, Scimitar reconnaissance vehicles, Stormer antiaircraft missile launchers, and Warrior armored personnel carriers.

Soldiers in a Yugoslav Army bus, headed east toward the Kosovo border, greeted the NATO convoy with obscene gestures. Near the cities of Urosevac and Stimlje, the Yugoslav Army stationed armored vehicles by the side of the road with flags waving in back.

In the town of Lipljan, which some NATO vehicles passed through, the Interior Ministry headquarters appeared to be fully staffed and the army had established a checkpoint on the north side of town. There, soldiers initially demanded that a carload of Westerners sing songs attesting to Serbia's power before instructing them to turn their car around and go back along the road the way they came.

The continuing lack of security meant that homecomings for many ethnic Albanians displaced by the conflict were wrenching. Reqica Shaban got to go home in Urosevac after moving around with his wife and daughter for three months. But he found his house still smoking from the fire that departing Serbian troops set only this morning. On Friday night, as he saw himself, it had been unharmed.

Inside today was broken glass so hot it melted, chunks of charred wood and collapsed cement. Every room of the three-story house was burned, some rooms still too hot to stand in, and out back, where the Serbian tanks had been parked, were patches of black, burned grass and strips of wood still aflame.

"I feel very bad. I have nothing more," he said.

In the blend of despair and hope that marked countless other homecomings today, Shaban added, "At least this is starting to be over."

Emboldened by the allied troops and tanks, scattered groups of other ethnic Albanians began making their way back to houses they, too, had been forced to abandon weeks or months ago.

"I saw NATO coming and I thought, `Freedom has returned,'" said Fatmire Hajrizi, 40. "The Serbs used our houses as their bases. They stole everything we had. What they didn't steal, they broke."

She stood with her husband and three daughters and her father at the side of a highway, waving to passing British cavalry troops. The scene was repeated for several miles in either direction, as the mood in many places was one of liberation. Old men doffed their hats, young women posed for pictures with the troops, and children tossed red flowers.

"I am happy, I love you a lot," yelled 9-year old Shkelzen as the troops passed through the village of Lugaxhi. Avdi Ejupi, 70, a resident of Komunasell, started crying as he stood at the side of the road and hurriedly said, "Thank you for coming. We couldn't go out. It was very hard. They cut my son in the throat and into pieces. We needed you badly."

The entry of the NATO forces contributed to a massive, chaotic traffic jam. Also lining the roads were departing Yugoslav troops and Serbian civilians, and trucks and civilian tractor-drawn carts loaded with household goods of ethnic Albanian families on the move.

The British vanguard force crossed the border from Macedonia, past a camp filled with more than 20,000 refugees from Kosovo, without incident. Only a few customs officers had come to work, and one of them said he had no idea what the future would hold. "I think it will be fine. We'll see," he said with a frown.

After moving slowly through a gorge in the Crna Gora mountains and across several long bridges where paramilitaries in green ski masks had robbed departing refugees in March and April, the lead British armored unit reached the town of Kacanik. As they arrived a series of Chinook helicopters was ferrying men and equipment to a football field in the center. Some of its homes had been badly damaged by shelling, but others appeared only to have been looted.

On a distant ridge line to the east, a group of Kosovo Liberation Army soldiers was seen leading away a man whose hands were bound. British soldiers had meanwhile set up submachine guns on tripods beneath restaurant and shop awnings, not far from wrecked homes with smashed windows and splintered telephone poles.

Later the battle group moved north past field after field that had been allowed to lie fallow and fill with weeds or wildflowers. A highway sign pointing to the city of Tetovo, an ethnic Albanian enclave in Macedonia, lay on its side. The smell of decaying animals began to pervade the hot air. The commander of the lead Challenger tank, Maj. Richard Hannay, evidently sensed more risk and swiveled the vehicle's 120mm cannon from side to side as he moved forward.

At the end of the day, NATO troops fell short of meeting their eventual goal of establishing a secure atmosphere in Pristina.

There, British Lt. Col. Mike Jackson had scheduled his victorious arrival news conference at the airport, only to postpone it several times. One reason for the delay was the obstacle posed by Yugoslav Army forces, who blocked any Western access to the facility along a main road. Well-armed paramilitaries also spent the evening harassing any Western vehicles that attempted to approach.

Another reason for the delay was the presence of the several hundred Russian soldiers who had arrived Friday without warning and without reaching an understanding with NATO about a Russian role in the peacekeeping effort. As dusk fell, a house at the periphery of the airfield burned despite a driving hailstorm.

The Army sentries at the airport appeared to take their orders from the occupants of a car with Belgrade plates and dark-tinted windows that was standing idle along the road not far from a tank stationed 30 yards away.

Yugoslav security forces could be readily seen not only at the airfield, but also along many roads in the area and in the lobby of the city's only functioning hotel. Even though Jackson eventually did hold his news conference, the mood of Serbs was not friendly, and gunfire from automatic weapons echoed through the city's empty streets until late this evening.

Staff writer David Finkel contributed to this report from Pristina.

CAPTION: In Kosovo town of Urosevac, Yugoslav Lt. Jozef Feher, left, hears British Maj. David Rose, right, order Feher's troops out of the Serbian province by today.

CAPTION: Ethnic Albanians hug and kiss British soldier Mark Hunter as he and his fellow troops make their way toward the Kosovo capital of Pristina in Yugoslavia. An electrician from Kosovo told the troops it was the happiest day of his life.

CAPTION: U.S. Marine Sgt. Jason Itro, a platoon leader from St. Petersburg, Fla., briefs troops in Skopje, Macedonia. Some 2,000 Marines are expected in Kosovo.