IN WHAT MUST BE the most bitter irony of the Balkan mess, refugees from Kosovo - the Albanian-populated province of Serbia now fighting for its independence - are beginning to arrive in Bosnia.

Bosnia, it should be recalled, is where Serbs perfected their tactic of "ethnic cleansing," later adopted by Croats and Muslims in a war that lasted nearly four years, killed more than 200,000 people and left 2 million homeless.NATO intervention halted the fighting in 1995 and the Dayton accord brought an uneasy peace, but it still has to be enforced by European and American troops who separate Bosnia's Serb republic from a Muslim-Croat federation strained by tensions of its own.

The federation is still crowded with Bosnian refugees who have not been able to return to their homes in areas captured by the Serbs. Now it also has to cope with an influx of ethnic Albanians from Kosovo - 5,000 at last count - who regard the non-Serb portion of Bosnia as being safer than their home province in Serbia.

Some 75,000 Kosovan refugees also have fled to Albania and Montenegro, which together with Serbia is all that's left of the former Yugoslav federation.

Ethnic Albanians make up 90 percent of the population of Kosovo. They had autonomy in Communist times but lost it in 1988 when Slobodan Milosevic - then president of Serbia, now president of the rump Yugoslavia - outlawed the Albanian language and replaced the province's Albanian-dominated civil service with Serbian officials.

A "shadow government" headed by Ibrahim Rugova tried to regain Kosovo's autonomy by negotiation but failed. The Kosovo Liberation Army surfaced in 1996 demanding more: full independence from Serbia.

Emboldened by a massive influx of smuggled arms stolen from the Albanian army, the guerrillas stepped up their attacks on Serbian security forces last year and even proclaimed a "liberated zone" along the Albanian border.

In February, Milosevic launched a military offensive in Kosovo with the stated purpose of "rooting out terrorists." But it smacked suspiciously of the "ethnic cleansing" he had engineered in Bosnia - artillery bombarded civilian villages said to be harboring KLA guerrillas, sending the inhabitants fleeing, then Serbian troops torched their homes so they had nothing to come back to.

In June, NATO jets staged mock air raids near Kosovo in a show of force designed to intimidate Milosevic into opening talks with the rebels. The six-nation Contact Group, originally formed to promote peace in Bosnia but now trying to resolve the Kosovo crisis, also imposed economic sanctions on Serbia (with Russia dissenting).

But diplomatic efforts to end the war have been stalled by KLA military successes. Having won control of 40 percent of the province, the guerrillas see no point in negotiating. Furthermore, their demands have broadened. No longer content with independence for their own province, they now want to create a new country composed of "the Albanian lands of Kosovo, Macedonia and Montenegro."

So far there has been no Albanian-inspired unrest in Montenegro. But Macedonia - home to a small United Nations monitoring force that includes 350 American troops - has suffered seven bomb blasts since the beginning of this year, some of them claimed by the KLA.

Autonomy is all the Western powers are prepared to support. The last thing they want is an irredentist Albanian state, allied with but not necessarily part of the "real" Albania, that shatters the existing borders of an already splintered Balkan region.

That's why Britain and the United States have backed off their threats of military intervention in Kosovo and diluted their support for the Albanian cause. NATO will only send troops, in the words of a Pentagon briefer, if "an outbreak of intolerable atrocities" demands their presence for humanitarian reasons.