BELGRADE — THE collapse of communism has unfettered deep religious and ethnic animosities in Balkan Eastern Europe. Nowhere in Europe is the danger of armed conflict or of the breakup of nations so great. Yugoslavia has come perilously close to civil war several times in recent months and appears destined to split apart soon. Its neighbors also still have much to settle. Minority ethnic Hungarians have clashed with Romanians in Transylvania. In Bulgaria, ethnic Turks still suffer after decades of persecution.
``The past hangs over the whole of politics in the Balkans,'' says Nikolai Todorov, one of Bulgaria's foremost Balkan experts. ``This heritage is very difficult to overcome.''
Large ethnic groups in the region had often been thrust into new states, suddenly finding themselves in the minority, he adds.
There are, for example, about 1 million ethnic Turks in Bulgaria. More than 2 million ethnic Hungarians live in Romania and ethnic groups are scattered across Yugoslavia.
Before being subjected to communist rule, Balkan borders and religious dominance shifted constantly in battles between rulers and their subjects, between the Orthodox faith of the southern Slavs, the Muslim creed of Ottoman Turks who dominated the southern Balkans for centuries, and the Roman Catholicism of Hapsburg rulers in the north.
As recently as 1989, hundreds of thousands of ethnic Turks were driven out of Bulgaria, the biggest emigration in four decades.
Although border revisions are unlikely in Romania and Bulgaria, visions of Yugoslavia's future range from civil war to a peaceful split into two very different nations - one like central Europe, the other Balkan.
Secession seems certain for the prosperous, pro-Western Yugoslav republics of Slovenia and Croatia. Leaders of the poorest southern republic of Macedonia and the central multi-ethnic state of Bosnia-Hercegovina have indicated they will follow Croatia and Slovenia if they secede.
Slovenia and Croatia favor a loose association of states. Yugoslavia is currently governed by an eight-member federal presidency made up of representatives from the country's six republics and two provinces.
The secessionist moves by Slovenia and Croatia have been rejected by communist-led Serbia, which seeks to keep a strong centralized rule. It is backed by the pro-Communist federal People's Army and its Serb-dominated officer corps.
Slovenian and Croatian officials cite Yugoslavia's decade-long inability to solve its deep ethnic, political, and economic crisis as the reason for their drive toward independence.
In January, the national Army almost came to blows with Croatia's secessionist leaders. At the same time, minority Serbs in Croatia vowed to fight what they called ``fascist Croat aggression'' against them.
Memories of World War II's fratricidal killings by Croat puppets of the Nazis, Serbian nationalists, and Communist Partisans spawn fears of new fighting to settle old scores. So far the violence has only been verbal. But it has been nearly hysterical between the 9.8 million Serbs and 5 million Croats.
``Spiritual genocide [is] being conducted against the Serbs in Croatia,'' says Serbian opposition leader Vuk Draskovic. ``Relations between Serbs and Croats are so bad that war can break out any time.''
Despite continued negotiations, Slovenia and Croatia appear to have given up on Belgrade. But they are also well aware of the pitfalls of independence. So far, no one has yet solved the problem of who will pay the federal foreign debt of $17 billion if the nation breaks up and financial accounts are settled.
For Slovenia and Croatia, however, Serbian President Slobodan Milosevic is the main obstacle. He came to power in 1987, achieved popularity with media control and nationalist policies, and overwhelmingly won state elections in December.
Opponents say the victory proves Serbia is nationalist, not European; Communist not democratic. Mr. Milosevic, they charge, wants to expand Serbian power.
``They are doing everything to make Yugoslavia disappear the way it is now and to have it reappear as Greater Serbia,'' says Stipe Mesic, Croatia's representative on the collective federal presidency.
Serbs are bitter that the late Josip Broz Tito, a Croat and Communist Yugoslavia's founder, dissected their territory into three regions: Serbia and the provinces Vojvodina and Kosovo.
Milosevic has since effectively reabsorbed both provinces, ignoring foreign protests over the deaths of more than 60 ethnic Albanians who battled mostly Serbian security forces in Kosovo. Such Serbian repression could soon backfire if democratic reforms take hold in Albania, which would certainly encourage Kosovo's ethnic Albanians to struggle for a union with Tirana.