In Vranovac, a hilly Pristina neighborhood that has shivered in fear for almost three months, ethnic Albanian residents did the unthinkable today.

They unfurled a red Albanian flag, symbol of the nation that borders Kosovo to the west -- and of the separatist aspirations of Kosovo's ethnic Albanian majority. They taunted Yugoslav soldiers and Serbian police in the street. And they screamed "never come back!" at hundreds of Serbian civilians fleeing Kosovo in fear.

The outpouring was one of several signals of the dramatic change in Kosovo -- a province of Serbia, Yugoslavia's dominant republic -- as NATO troops began to take up positions as peacekeepers and Yugoslav and Serbian forces started to withdraw. As the tide of Serbian dominance in Kosovo recedes at a breathtaking pace, Albanian nationalist sentiments and hopes are quickly surfacing, and euphoria at NATO's arrival is giving rise to feelings that ethnic Albanians will soon be in charge.

If the demonstration in Vranovac was an accurate gauge, the separatist Kosovo Liberation Army stands to cash in on NATO's presence. People here expect the rebel force, which was largely scattered when the Belgrade government launched a scorched-earth offensive against them in late March -- to reemerge as a political force.

The 1,500 revelers here linked NATO and the KLA in their chants. They sang a KLA theme song that proclaims, "Kosovo is ours. Dead or alive, we will support it." All the while, they placed roses and other flowers on the chassis of a British tank parked at the entrance to Vranovac.

No more than four days ago, any of these gestures would have been impossible. Belgrade stripped Kosovo's Albanians of their autonomy a decade ago, and the Serbian minority has dominated life in the province ever since. When the struggle between the two peoples came to a head with the NATO air campaign and the expulsion and killing of ethnic Albanians, the only nationalist chanting here was done by Serbs. Except for brief trips to the market, ethnic Albanians generally stayed off the streets. Talking to police, even to clear up uncertainties about whether to stay or flee to exile, was taboo. Mention of the KLA was dangerous.

Even as recently as the pre-dawn hours Saturday, Pristina's Serbs swarmed to greet Russian troops as Slavic saviors. There was not an ethnic Albanian in sight, and the flag being unfurled was Serbia's.

Now, the tide is turning -- and both sides know it.

"For the first time, we can get out of our homes freely," said Diana Dacani, a homemaker in Pristina's Dragodan neighborhood who had come to Vranovac to witness the deployment of British peacekeepers. "We don't have to keep our feelings to ourselves. We never want to do that again," she said. "It's true that some of these feelings will not be very nice. From my balcony, I still see houses being set on fire all over the valley. So how are people to feel?"

On the street, an amazing scene unfolded. A tractor carrying four Yugoslav soldiers armed with AK-47 assault rifles rolled down the hill. The crowd surged forward. Everyone made the two-fingered V-for-victory sign, which also expresses Albanian nationalism here. Obscene expressions streamed from the mouths of little boys. Women hooted.

Then trucks and sedans bearing Serbian civilians from the western Kosovo city of Prizren drove up. The crowd jeered and gestured at them to move on. A forest of insulting, one-fingered gestures sprouted on both sides of the road.

"A lot of the Serbs did bad things; certainly, the police and paramilitary people cannot come back," said Amer Mustafa, who once worked here for human rights observers from the 55-nation Organization for Security and Cooperation in Europe. "I feel bad for these refugees, but we did not drive them out. They are leaving on their own."

Serbs here, both military and civilian, are rapidly growing more and more uncomfortable. Yugoslav soldiers discuss among themselves the dangers of the KLA. At the Grand Hotel, a shabby structure teeming with foreign journalists, ethnic Albanian interpreters who arrived with reporters from Macedonia spread rumors of threats to Serbian interpreters working with journalists. People whose cars bore license plates from Serbian towns stripped them off.

Mustafa said that the KLA had not returned to Pristina, the Kosovo capital, where it had carried out a violent campaign against Serbian police in the months leading up to the NATO airstrikes. "That's a decision that will be made on a high level. The KLA will not create difficulties for different nationalities. They will only come to protect the people," he said.

But the KLA already may be in Pristina. This morning, gunmen shot and killed a policeman, two soldiers and a civilian in a car near Vranovac, according to Yugoslav officials. There was a telling detail in the announcement that pointed to the shifting balance of power here: The usual roundup of ethnic Albanian suspects did not take place.

CAPTION: Refugees reach out to welcome truckloads of U.S. Marines at the Stenkovic camp in Macedonia as the Americans made their way to neighboring Kosovo.

CAPTION: Ethnic Albanians shred a Yugoslav uniform and flag after crossing into Kosovo from Albania at Morina Pass. German troops crossed, then refugees reentered the province from which they had been driven.