If Bill Clinton, having won the war in Kosovo, is to win the peace, then he needs to think a lot bigger than he has thought so far about a diplomatic settlement. It was necessary -- to put out raging fires -- for him to take an emergency single-country approach as he did earlier in Bosnia and now in Kosovo. But to make these diplomatic achievements last and to settle down the whole Balkan region, he must move carefully to a larger stage.

"The problem" is not just how to fix a broken Bosnia or Kosovo. It is how to organize all the fractious and conflict-prone South Slavs. Understanding this prime requirement, Woodrow Wilson after World War I lumped them together as best he could in a new Yugoslavia. Understanding this requirement even more deeply, Communist leader Josip Broz Tito after World War II extended the effort in his sometimes murderous, otherwise manipulative fashion.

Yugoslavia can never be put back together on any past design. But the rationale for reconstitution remains valid: to serve the inextricably interwoven community, security and economic needs of all the South Slavs.

The Dayton accords on Bosnia may have demanded too much too soon by way of ethnic cooperation in the worthy name of opposing "ethnic cleansing." The Kosovo peace plan merely papers over the explosive difference between affirming Serbian sovereignty and dangling Kosovar independence. These are improvised and unstable arrangements that need a firmer base.

Former Henry Kissinger aide William G. Hyland, writing on this page on March 31, urged the European powers -- without the United States -- to create a security system to satisfy contending nationalist forces. He would do it at the sort of summit the Great Powers convened in Berlin in 1878 to redraw the map of the Balkans. This admittedly imperfect initiative "avoided the threat of major war and provided for several decades of peace" -- pretty good for the times, though it ended badly.

Kissinger himself (Newsweek, June 21) sees the Kosovo peace plan as caught between irreconcilable offers of Kosovar independence and continued Serbian sovereignty. He argues: "It would be far wiser to cut the Gordian knot and concede Kosovar independence as part of an overall Balkan settlement -- perhaps including self-determination for each of the three ethnic groups of Bosnia. In such an arrangement, the borders of Kosovo and its neighbors should be guaranteed by NATO or the Organization for Security and Cooperation in Europe."

Veteran Balkans hand Dan Morgan of The Washington Post suggests [op-ed, June 16] that "dangerous Serbian nationalism is not a given. It dissipates in a political environment in which Serbs feel secure. How to recreate such a climate after Serbs have done so much to threaten the security of others is the next challenge for the international community. European models abound. France and England embraced Germany within NATO and the European Union after World War II. In the Balkans there is also a model: the old Yugoslavia. It cannot ever be reconstituted as it was. But it provides a structure for the integration of economic and security interests that could heal wounds and contain Serbia's demons, if men of goodwill in Belgrade and Zagreb decide to make it work."

All this is not to minimize the role American diplomacy played in putting out those fires in Bosnia and -- even more a work in progress -- in Kosovo. Lives have been saved, and valuable time has been earned to work on the larger canvas.

There the priority must be to enable peaceful and equitable change in areas of Balkan public life known more for generating violence. I refer in particular to the vexing question of whether to encourage or discourage the redrawing of national borders on ethnic lines.

All possible answers promise trouble. The best answer is: Redrawing borders is unacceptable except when other compensations are available for the losers. Example: A post-Milosevic Serbia might yield Kosovo but gain Bosnian Serbia. That is the sort of trade-off available on the larger field. A big international conference might bargain out the interests of Serbs and Kosovar Albanians, with the results guaranteed by the full swath of interested nations.

Bill Clinton does not actually need another diplomatic project. The reasons for considering it anyway have to do with building peace in a still troubled region and showing American leadership.