ROME — Kosovo's declaration of independence has touched off an all-too predictable spasm of violence and hostility in a region that emerged from devastating war scarcely a decade ago.

From an American Embassy in flames in the Serbian capital of Belgrade, to stone-throwing at NATO troops along the new unsteady border between Serbia and Kosovo, the anger of Serbs over the loss of a region they consider their cultural heartland is intense and dangerous.

And the U.S., which pushed for Kosovo's separation from Serbia and was among the first countries to recognize the new nation, will receive the brunt of Serbian fury. Far from stabilizing the region, as the Bush administration forecast, the move by Kosovo has launched a period of volatile uncertainty.

Riots in Belgrade on Thursday night, which left one person dead, 150 injured and more than 200 arrested, were the largest outburst of anti-Western rage since before the fall of dictator Slobodan Milosevic in October 2000.

The unrest represented what Ljiljana Smajlovic, editor of Serbia's influential Politika daily newspaper, said was a "tectonic shift" in Serbian public opinion that will carry far-reaching and unpredictable consequences.

Still, she and other Serbian analysts said in interviews that an all-out war does not appear to be among those consequences for several reasons.

First, Serbia's military capacity is far diminished from the days when the then-Yugoslavia fielded Europe's fourth-largest army. Many of its generals and commanders ended up at the international tribunal at The Hague, charged with war crimes, because of the bloody campaigns they led to repress the breakaway states of Croatia and Bosnia-Herzegovina.

And ethnic Albanians who dominate Kosovo and who deployed a ferocious guerrilla army to fight for their independence are on their best behavior while receiving favorable treatment from Western powers.

Second, there are 16,000 NATO troops deployed in Kosovo, plus a U.N. police force to give pause to any military challenges. The presence of international forces stands in marked contrast to 1992 Bosnia, for example, when civilians were left largely to the mercy of Serb paramilitaries, which resulted in three years of bloodletting before NATO stepped in to help stop the killing.

Perhaps most important, Serbia is a changed place. Milosevic, the architect behind most of the warfare of the 1990s, is dead. The past eight years in Serbia have seen the rise of pro-Western, democratic leaders who have fostered political reforms.

But many pro-Western leaders of Serbia now feel betrayed.

They spent the past few years extolling the virtues of Western international law and justice that included, they point out, the 1999 U.N. resolution that establishes self-rule for Kosovo but as part of Serbia. They see as the epitome of hypocrisy that Washington went around the U.N., sidestepping the Security Council because of Russian opposition, to approve Kosovo independence.

Many of the fiercest demonstrators torching embassies Thursday night and shouting "Stop U.S. terror!" were young protesters who might have little memory of Milosevic but who came of age as NATO was bombing Belgrade in 1999 to punish Serbia for its attacks in Kosovo.

Cedomir Antic, a historian with the Institute for Balkan Studies, noted that in elections earlier this month, the ultranationalist Radical Party, while narrowly losing, had managed to quadruple its vote over balloting in 2001, in part because of Kosovo.

"People are very frustrated," Antic said. "The Serbian government is very united on the issue of Kosovo but very divided on where to go from here."

The division weakens the ruling democratic coalition and makes it likely the government will fall and the pro-Moscow Radicals, whose president is also on trial for war crimes at The Hague, will take over.

What seems most likely, however, is that low-intensity skirmishes along the Serbia-Kosovo border will continue unabated.