LONDON -- Ever since the Federation of Yugoslavia broke up a decade ago, the fate of the territories over which Marshal Tito ruled for most of the postwar period has provided not just an internal cycle of war and separation, but also a series of major challenges for the international community, in particular the 15-nation European Union.

Marked by the legacy of the empires of the Ottoman Turks and the Hapsburg Austro-Hungarians, the region stretching down to Greece has a specific character and ingrained enmities that are foreign to more settled areas of the continent. Having failed to take sufficient early action in the face of atrocities and ethnic killing, particularly in Bosnia, the European Union and the United States came to feel responsible for preventing further bloodshed and oppression by the Serb government in Belgrade, using military air power of the NATO alliance as its enforcer.

NATO's Kosovo action, however, showed the limits to the risks Western governments were ready to take to try to help bring peace and order to the Balkans. The demonstration of ultra-sophisticated force from on high, together with the threat of war crimes trials for those responsible for atrocities and ethnic cleansing, was intended to cow the warring factions and racial groups into behaving in a manner more in keeping with 21st century Europe.