The unraveling of Macedonia is a humanitarian crisis with great strategic and historical significance. What happens in the squalid, grimy streets of Macedonian villages now directly affects the future expansion of NATO that President Bush has spoken so eloquently about.

In the coming months, in preparation for the Prague summit of 2002 -- the first NATO summit in a former Warsaw Pact state -- the Bush administration will set the parameters of a second post-Cold War enlargement of NATO. The first enlargement, orchestrated by the Clinton administration, brought Poland, Hungary and the Czech Republic into the alliance. Because those countries were part of historical Catholic-Protestant Central Europe, it was an expansion that had the logic of culture and tradition on its side. But the next enlargement, if it occurs, could be far more decisive for the future of Europe, because it may not necessarily reflect historical and cultural trends as much the particular vision of a few men and women. And the dirty little war between criminalized Albanian guerrilla gangs and a depressingly weak Macedonian government is, as I write, both shaping and constraining their options. One cannot call for NATO expansion into Romania and Bulgaria while letting a full-scale ethnic conflict erupt next door in what many consider "historic western Bulgaria."

NATO might expand in two different ways. Were expansion limited to Slovenia, Slovakia and some of the Baltic states, the map of Europe would vaguely resemble that of the medieval Christian West, with the Orthodox world mainly frozen out. That would institutionalize a civilizational divide that is fast replacing the Cold War one.

But NATO might also expand both to the northeast and the southeast, that is, into Romania and Bulgaria, two Eastern Orthodox states potentially undermined by instability in the former Yugoslavia. The latter option would not only encircle the former Yugoslavia with more stable and democratic states, it would lead to a truly diverse Europe.

The United States should welcome more ex-communist states in NATO. Public opinion in those countries -- because of awful memories of communism -- is far more pro-American than in Western Europe, where populations have long been pampered by social welfare systems (made possible by U.S. military hegemony after World War II) and have thus lost the sense of the tragic, without which realistic thinking in foreign affairs is unlikely.

Moreover, a smaller, more culturally cohesive Europe like the one that exists now will be much more inclined to define a vision of the West opposite to ours, as both America and Europe become prone to a narcissism of small differences.

Finally, with a window on the Black Sea, NATO might be in a better position to police the movement of contraband and Russian organized crime,

As long as southeastern Europe is not brought under the Western security umbrella, these countries are up for grabs through Russian-sponsored subversion. Bringing Romania and Bulgaria into NATO might subdue Russian ambitions in the region. After his meeting with Bush, Russian President Vladimir Putin flew directly to Belgrade and Kosovo. Nobody should delude himself that the Russians aren't keen on retaking their historical "near abroad" in the Balkans.

But a grand vision is impossible if the former Yugoslavia is treated with benign neglect. The humanitarian crises in this region have always been in a separate category -- not because they are inside Europe and involve white people but because issues of power and strategy are involved that never applied in places such as Rwanda and East Timor. By intervening, albeit belatedly, in Bosnia in 1995, the Clinton administration helped change the debate from "Should NATO exist?" to "Should NATO expand?"

The Bush administration must prepare to avoid the public relations and foreign policy nightmare of intercommunal violence in the streets of Skopje, eliciting the melodramatic sanctimony of television correspondents as 38,000 NATO troops stand by a few miles away in Kosovo and the United States gives the appearance of doing too little, too late.

History is often made incrementally -- not through grand, sweeping judgments but through the relegation of seemingly small matters. In terms of social and economic development, the southern Balkans is closer to the Third World than to the heart of Europe, but it is also the only area where NATO has ever been involved in a war. If Washington and Brussels don't take strong action in Skopje, then Skopje may end up constraining Washington and Brussels more than anyone can now imagine. Macedonia and the future borders of NATO are two issues that cannot be decoupled.