When Russian tanks started rolling through this dusty crossroads in western Kosovo last week, the villagers greeted them with boos, jeers and high-pitched whistles--a sure sign of derision among ethnic Albanians.

A few miles south in the larger town of Orahovac, crowds of up to 10,000 have gathered daily in the shadow of a bullet-scarred mosque to chant anti-Russian slogans. Thousands more have hectored and thrown rocks at Russian paratroopers in Kosovska Kamenica, a village more than 50 miles to the east.

The arrival of several hundred Russian troops as peacekeepers in Kosovo last week added a dicey new problem to the challenges facing NATO stabilization forces here.

Ethnic Albanians widely distrust the Russians because of their close ethnic ties with the Serbs and because of Moscow's support of the Serb-led Belgrade government during NATO's 78-day bombing campaign against Yugoslavia. Many now fear that Russian troops will seek to protect Serbs who committed war crimes. "We have suffered a lot from the Serbs here, and they have always been under the Russian umbrella," said Auni Mazreku, 23, a market owner in Malisevo. "We hate them the same as we hate the Serbs. There will be trouble here."

Many of Kosovo's remaining minority Serbs, on the other hand, view the arrival of Russians as a godsend--hoping they will protect them better than Western peacekeepers from vengeful attacks by ethnic Albanians. At the Russian encampment in the U.S. administrative sector of eastern Kosovo last week, for example, dozens of Serbs milled around the gate pleading for favors or protection.

"We cannot go to [Slobodan] Milosevic or anyone else," said Borislav Cvetkovic, 45, a farmer, referring to the Yugoslav president. "Only the Russians can help us now."

As part of an agreement with NATO that helped forge last month's peace settlement with Belgrade, 3,600 Russian troops are to deploy alongside NATO forces in three allied-controlled sectors in Kosovo. About 32,000 NATO troops have arrived, the core of a force that will ultimately exceed 50,000.

Many NATO and U.N. officials say the Russian presence could mitigate the concerns of Serbs that they are not safe among the ethnic Albanians--a people Miolsevic's Serb-led government tried to purge from Kosovo. At the same time, some worry that local hostility toward the Russians could undermine NATO's good relations with the Kosovo Albanians and heighten ethnic tensions.

"I don't think we will lose any credit because of this issue," said Dutch Maj. Jan Joosten, a NATO spokesman. "The Albanian people here in Kosovo should not forget that the Russians played a major role in ending the war here. . . . They are expected to be evenhanded toward ethnic Albanians as well as Serbs, and we have no reason to believe they won't be."

At the Russian compound in Malisevo, where several dozen Russian army troops set up camp last week a couple miles from town, Lt. Col. Aleksandar Sizikh said he and his men are aware of the ethnic Albanians' suspicions. His troops are roundly booed whenever they go through town, but Sizikh said he hopes to change peoples' minds.

"They may be against us, but we are providing the same mission" as NATO, said Sizikh, who noted that he previously had commanded peacekeeping troops in Croatia. "We will provide help to all of the population, no matter who they are. The opinion of the population will change with time."

Substantial numbers of Russian troops, mainly paratroopers, began arriving in Kosovo earlier this month, and the full contingent is expected to be here by mid-August. Several hundred Russian soldiers had been stationed at the airport outside the provincial capital, Pristina, since June 12, when Moscow rushed them into Kosovo ahead of the first NATO forces.

Western officials stress that the Russians will serve under NATO command, with Dutch and German soldiers around Orahovac, with U.S. troops in Kosovska Kamenica, and with French forces in the Srbica-Lausa area. "It's not like they'll be [out] on the back forty by themselves," said Brig. Gen. John Craddock, commander of the U.S. peacekeeping detachment. "They will be under my tactical control. That will mean I will tell them what they do and what they don't do."

Such assurances haven't calmed the fears of many ethnic Albanians. In Orahovac, mathematics teacher Lirie Kasadi has shown up for anti-Russian protests every day. Kasadi and others point to evidence that some Russian mercenaries fought along with Serbian paramilitary units as they plundered Kosovo.

"We are most afraid that the ones who committed the atrocities here will be let go," said Kasadi, holding his three-year-old daughter on his shoulders as he marched with protesters last week. "We don't have anything against the other peacekeepers, but the Russians must go."

Up a steep hill from the cobblestone streets where Kasadi and others were protesting, Serbian residents huddled in their doorways and complained that Dutch troops have done little to protect them, whether from kidnappings or from bottle-throwing youths.

"The situation needs to be improved," said Grkovic Nebojsa, 47, a metalworker. "The way things are now, they can't protect us enough. . . . There are no such things as war criminals here, and the Albanians know it, but they still attack us."

Here in Malisevo, the Russian troops have begun conducting patrols and manning checkpoints with Dutch and German peacekeepers. Capt. Henig Klement, a German army officer, said there have been "little conflicts" between Russians and civilians but nothing serious. "I tell my soldiers to be careful," he said. "You don't always know what the reactions will be with the Russian presence here now."

Correspondent Karl Vick in Pristina contributed to this report.

CAPTION: Russian troops march along a road near Malisevo. NATO hopes the Russian presence in Kosovo can calm Serbian fears of reprisals by ethnic Albanians.