THE end of the East-West cold war finished off the Yalta and Potsdam agreements on how Europe should be arranged after World War II.
Now the East European liberation euphoria of 1989 and 1990 has subsided, undoing even the previously more stable elements of the peace that followed World War I.
The first notable victim was Yugoslavia, which already is in the final throes of disintegration, spreading fear through the Balkans in the process.
Now, as a result of the Slovak nationalists' heady election victory in early June, Czechoslovakia seems set irrevocably toward a similar split. In 1918 this union of Czechs and Slovaks was the democratic centerpiece among nations of the collapsed Hapsburg empire.
Until this constitutional crisis, Czechoslovakia's radical economic reform program offered an orderly model for stable change to be envied by the other former communist states. The reform obviously will have new difficulties.
At best it will be delayed for the three months the Czechs and Slovaks have to make up their minds about the terms of the "divorce." In the meantime, foreign investors will wait.
Outside Czechoslovakia, separation will have a ripple effect unsettling to Central Europe generally and neighboring Hungary in particular. Inside Slovakia, it is being greeted with dismay by the half-million resident Hungarians whose call for rights guarantees under independence has already been rejected by the nationalists.
Neither of the former East bloc states, nor the non-Serb remnant of the old Yugoslavia, is immune to this highly emotional, irredentist, and often religious chauvinism that has mushroomed up under the cloak of the new democracy.
Under communism, ethnic problems were buried beneath a facade of "comradely" alliance. Hungary, for example, consistently ignored nationalist agitation to confront Romania over 1.7 million Hungarians suffering discrimination in Transylvania.
Today, Bucharest's post-communist government, calling itself democratic, balks even at talking with Hungary about it. In fact, it finds convenient common cause with Slovakia and with Slobodan Milosevic's Serbia, where Hungarians and Albanians were stripped three years ago of what autonomy they had.
For many years, the former Yugoslavia was seen as an ethnic "Joseph's coat" sewn together with an adroit mix of central authoritarianism and common advantage. The latter counts little in Eastern Europe these days.
The sole bright spot is Bulgaria which seems to have learned that democracy includes ethnic tolerance and has largely restored the rights its Turks lost under communism.
Elsewhere the picture is very different. Albanians and Hungarians are menaced anew in Serbia; Hungarians in Slovakia and Romania; and a Serb move against Macedonia, the fourth ex-Tito republic to secede, is increasingly possible.
The last would undoubtedly set the Balkans alight unless a more supportive West helps Macedonia stand firm by overriding the Greek veto on European Community recognition.
In general, the West holds a vital key. It disregarded the merits of a continued united Yugoslavia. The Bosnians, after 5 months, still call vainly for more positive United Nations intervention.
In their current crisis-ridden plight, East Europeans have little hope of Western economic support. Yet it is essential if they are to attack the causes of such dangerous nationalism. Czechoslovakia has already encountered this reluctance.
Nor should the West expect the malaise to go away without aid and without stronger international intervention than diplomatic rebukes and modest sanctions against Serbia.
It may look localized. But this has often been the case in the history of Central and Eastern Europe.