MUCH BLOODSHED has resulted in this decade from the spinning off into independence of the various republics that used to be components of Yugoslavia. More than once the resulting turmoil has drawn a reluctant United States into war or peacekeeping duties. So when one of the last two republics still inside Yugoslavia begins talking about separation and autonomy, it probably makes sense for Americans to pay close attention.

Last week, Montenegro, junior partner to Serbia inside the truncated Federal Republic of Yugoslavia, asked for substantial new powers within the federation. If these were not granted, Montenegro's government suggested, it would be forced to hold a referendum on independence. The powers requested do not fall far short of independence. Montenegro said it would remain within Yugoslavia -- but it wants a separate currency, separate foreign ministry and separate army command.

In a broad sense, Montenegro's gambit is just the latest inevitable response to the brutality and malevolent nationalism of Slobodan Milosevic and his regime. Mr. Milosevic, formerly president of Serbia and now president of Yugoslavia, portrays himself as a champion of Greater Serbia, with the paradoxical result that the territory he rules over becomes smaller and smaller. Slovenia, Croatia, Bosnia, Macedonia and Kosovo have each in turn slipped his bonds; a divorce from Montenegro would represent the final disassembly of the federation he claimed to value. A more democratic and tolerant leader might have kept many of the pieces together.

Montenegro for some time now has provided an encouraging contrast to the authoritarian Milosevic regime. Its elected president, Milo Djukanovic, supports the establishment of democratic institutions. Montenegro has provided a haven for Serbian democrats chased out of their homeland by Mr. Milosevic. Perhaps even more significant, Montenegrins -- who differ hardly at all in ethnic terms from their Serb neighbors -- provide encouraging proof that Mr. Milosevic's poisonous rule is not the only kind that will take root in Balkan soil. And Montenegro vigorously supported NATO during the fight to protect ethnic Albanians in Kosovo from Mr. Milosevic's depredations.

Now Montenegro has practical reasons to distance itself. Serbia's economy is plummeting; Montenegro cannot afford to be tied to its currency. President Djukanovic also has sound political reasons to distance himself from Mr. Milosevic and to protect his country from the troops Mr. Milosevic controls. NATO and the United States have supported Montenegro in its efforts to win more autonomy; they also have counseled against any reckless declarations of independence that could set off another round of killing.

The hope now is that Montenegro's pressure will be one more factor persuading Serbians that they would be better off without Mr. Milosevic. The worry is that a cornered Serb dictator will seek to save himself by lashing out once more. The United States and its allies should be preparing for both possibilities.