When NATO tanks rolled over flower petals tossed by adoring crowds and assumed control of Kosovo on June 12, Ilir Muhadri jubilantly welcomed the peacekeepers. Today Muhadri and other young ethnic Albanian young men glared at French troops who guarded a bridge that separated a Serbian enclave from the rest of this divided city.

"I can say with full confidence that they are on the side of the Serbs," said Muhadri, as he stood some 30 yards from a French checkpoint on the bridge, the site of violent clashes between the peacekeepers and ethnic Albanians attempting to storm the Serbian side in recent days. "They were always sympathetic to the Serbs."

It hasn't taken long -- eight weeks -- for the bloom to come off liberation. With Kosovo purged of nearly 80 percent of its Serbian population and with many of the remaining Serbs, particularly those in urban areas, now viewing international peacekeepers as their last and only protection, the NATO-led peacekeeping operation is confronting an unexpected phenomenon: ethnic Albanian hostility.

The peacekeepers' determination to maintain a multi-ethnic society here has led to violent confrontations with ethnic Albanians bent on revenge against the Serbs or the looting of their property. And the United Nations' insistence on the primacy of its authority has increased tension with the Kosovo Liberation Army, an ethnic Albanian militia that is attempting to establish its own parallel system of control in Kosovo, which formally remains a province of Serbia, Yugoslavia's dominant republic.

In the past few days alone, American, British, French and Russian peacekeepers have all had tense, armed confrontations with the local ethnic Albanian population. Russian soldiers have been singled out for attack because of the perception that they are particularly supportive of the Serbs. A Russian soldier was shot in the shoulder by a sniper Thursday, the second wounded in the past week.

The affection of the general population remains with NATO, which waged an 11-week air war to drive Serb-led security forces from Kosovo on behalf of the province's ethnic Albanian majority. But the western alliance faces a delicate task in its efforts to establish order, observers said. It cannot alienate the ethnic Albanian community with a Draconian crackdown yet it needs to contain the rebel army, which it now suspects is the main source of much of the lawlessness.

"KLA radicals are restless and acting unilaterally," said one Western diplomat. "The KLA leadership has made all the right noises about establishing democracy, but they don't seem to be able to control their membership. And that could be very dangerous" for the peacekeeping force.

Some members of the KLA, which fought an 18-month guerrilla war for Kosovo's independence, believe it is being snubbed by the United Nations and denied the privileges within Kosovo that it felt would flow naturally because of its battle against Serb-led Yugoslav forces, which precipitated NATO's 78-day air campaign. And Western officials, in a parallel sentiment, increasingly fear that the violence is driven not by retribution against Serbs, which potentially can be contained, but raw greed -- as militia members and criminals vie to grab position and property in an environment of lawlessness.

The KLA's so-called minister of the interior, Rexhep Selimi, was detained by British troops after he waved a gun at them while driving a car with a flashing police light. A later raid on the offices of Selimi -- an uncle of the KLA's former military commander -- produced several weapons and identity cards giving the bearer the right "to conduct illegal activities, including carrying and using weapons, entering and confiscating property without warning," British troops said.

KLA officials have also incited demonstrations in Kosovska Mitrovica against French troops, who have blocked access to a section of the city containing an entrenched Serbian population, French troops said. One French soldier was seriously injured when he was struck by ethnic Albanian demonstrators.

In the past few days, peacekeeping troops have detained nearly a hundred people and seized dozens of weapons. Italian Foreign Minister Lamberto Dini accused the KLA this week of failing to honor its agreement to disarm.

A KLA official rejected much of the criticism, arguing that though the United Nations has rejected the rebels' authority over the province, it still expects the KLA to serve as the provincial police force. The United Nations "keep saying they're in charge, but they're doing next to nothing," the KLA official said. "At the same time, we're to blame for everything. As you like to say: Go figure."

Western officials, however, believe that the KLA has been involved in repeated attacks on Serbs and peacekeepers. Russian troops are being shot at on a nightly basis, according to Maj. Konstantin Konovalenko, an officer stationed at Pristina airport. "The situation is very bad for our troops," Konovalenko said.

Ethnic Albanians accuse the Russians and French of sheltering Serbian paramilitaries -- a charge rejected by KFOR, the NATO-led Kosovo protection force. "We don't have a problem with KFOR, just the French and Russians," Muhadri, the young ethnic Albanian, said.

But British and American troops have also been involved in confrontations with ethnic Albanians recently. British troops shot and wounded three ethnic Albanians during a firefight Thursday morning when they found seven of them attempting to evict a Serbian family from its home just north of Pristina, the Kosovo capital.

U.S. troops had to come to the aid of Russian peacekeepers faced by hundreds of ethnic Albanians armed with rocks and sticks on Wednesday. That followed a confrontation between U.S. soldiers and ethnic Albanian protesters Tuesday in the southeastern town of Gnjilane after Americans arrested armed members of the KLA.

U.N. administrator Bernard Kouchner issued a decree Thursday that allows U.N. police and peacekeeping troops to detain people deemed a threat to public order for up to 12 hours, removing them from their hometowns or even deporting them temporarily from Kosovo.

Hansjoerg Strohmeyer, Kouchner's legal adviser, rejected suggestions that the decree would impose police state conditions in Kosovo, saying, "The tool is limited to a maximum of 12 hours. Practically speaking, it allows us, as in other countries in Europe . . . to remove people who are instigating, through hate speeches or other forms of provocation, unrest or violence, within 10-15 minutes."