THOUGH there is a relative lull, except in Yugoslavia, 1991 already sees the Balkans mired in old, historic feuds. The problems are deep enough to indicate how easily the region could slip back toward its turn-of-the-century reputation as a powder keg endangering Europe's stability and balance.
At that time, big-power strategic rivalries in the area were active, along with regional ethnic animosities, until the shots in a Bosnian town in 1914 engulfed Europe in World War I.
The war changed the map of the continent, but the local hates lingered on until World War II, after which they were kept under the rug for 40 years by the new communist order.
Ironically, today's post-communist structures in Eastern Europe have opened the way not only to free elections but also to renewal of ancient antipathies and nationalist extremes - above all, in the traditional cockpit Balkans.
In the new post-election era, it seemed at first that more sophisticated Czechoslovakia, Poland, and Hungary might be spared. Now, however, they, too, are drawn into a growing spread of minority tensions and other problems.
Czechoslovakia, for example, is suddenly beset by a vehement Slovak separatist movement out to dismember Thomas Masaryk's 73-year-old state born of World War I. Slovakia is also in bitter conflict with Hungary over the latter's reneging on its share in a joint hydroelectric power project on the Danube.
Hungary, for its part, is again sparring acrimoniously with neighboring Romania over its province of Transylvania, where last year's new freedoms have failed to meet Budapest's expectations of a better deal for the region's large Hungarian population. It is a decades-old dispute.
Last month's visit to Bucharest by French President Fran 141&gt;ois Mitterrand caused concern in Budapest. He went to promote his concept of a confederated Europe, but his visit was a considerable international boost for his hosts and Budapest feels a setback.
Eastern Europe is no longer a monolith and divisions are showing up everywhere. The Central Europeans - as Warsaw, Prague, and Budapest see themselves - have center-right governments moving them resolutely toward full-fledged market economies. In Bulgaria, Romania, Serbia (the biggest Yugoslav republic), and Albania, the communists are still very much in place.
In fact, both in north and south, the stability of new structures can be weakened by the reemergence of ethnic enmities and cross-border issues. The worst danger is in the Balkans, where - ironically - Yugoslavia, longtime frontrunner of reform, again presents the most sinister hotbed of discord.
Under the so-called collective leadership that succeeded Josip Broz Tito in 1980, Yugoslavia had "eight of everything" - eight republican or regional governments, eight communist parties, and eight economic programs, based on local ambitions in near total disregard of mutual interest.
An aggressively nationalist Serb communist leadership prompted first an armed crisis in Kosovo, then a constitutional crisis with secessionist Slovenia and Croatia for opposing Serb demands to retain a centralized federation that Serbia could dominate. Today's crisis is further aggravated by several parallel constitutional orders in the republics, all - to quote Belgrade's Review of International Affairs - "on collision course."
Only Federal Premier Ante Markovic seems interested in using parliament to establish constitutional changes for the sake of a crucial common economic reform, on which International Monetary Fund aid - vital to every republic - is based.
The Serbs, however, want territorial adjustments to gather all Serbs living in other republics into a "greater" Serb state. This, says the commentator just quoted, is "the problem of all problems"; if compromise fails, it could be the last step before civil war.
In contemporary Europe, this is unlikely to start another war. But it could unleash disturbing nationalisms in the newly liberated half of the continent.