By William G. Hyland The Washington Post

WASHINGTON - The president has put America in a virtually impossible position. It cannot escalate without grave risks.

If the president and NATO truly want to halt ethnic cleansing, the alliance will have to put in a large ground force, or at least mount a credible threat to do so. A conventional ground war in the mountains of Albania and Kosovo will quickly degenerate into a quagmire.

On the other hand, the United States and NATO cannot retreat without humiliation that could have dangerous consequences not only in the Balkans but in Europe and even in Asia.

The only real alternative is to revive international diplomacy.

The Clinton administration's so-called peace plan is dead. It would be insanity to turn Kosovo back over to lethal Serbian rule, no matter what the degree of ''autonomy.'' It is also implausible to introduce a NATO peacekeeping contingent on Serbia's borders after bombing that country.

The way out is for Washington to recognize that the problem is preeminently a political one; military pressure will help but cannot be the solution. Second should be the recognition that the crisis is no longer a Balkan affair but a pan-European problem that cannot be solved by NATO alone.

Yugoslavia has become the sick man of Europe. It cannot be put back together; but the European powers could reconstitute a security system that might satisfy contending nationalist forces. President Bill Clinton should take a page from history and do what European leaders did in the last century: convene a European summit conference, as the Great Powers did in 1878 at the Congress of Berlin.

Then as now, the purpose would be to redraw the map of the Balkans and avoid an all-out war. Not just the United States but all of Europe, including Russia and Ukraine, should devise a peace plan for the Balkans.

Kosovo is the most urgent issue and obviously will have to be a central element. There is no geographical or historical reason to treat Kosovo as sacrosanct; it will have to be partitioned. One part, probably the largest, should become independent. But for some defined period it should not be permitted to join Albania.

The other part of Kosovo, along the Serbian border, should remain under Yugoslav sovereignty, but as a demilitarized security zone. The capital, Pristina, might become a free city under UN auspices for, say, a few years. Some military forces would have to be inserted into independent Kosovo to man the partition line, to protect the Serbian minorities that still will reside there and to guard sacred Serbian historical sites.

Guarantees would have to be negotiated to protect all parties, especially Macedonia and Montenegro. All the Balkan countries would have to join that guarantee, in particular the Greeks, Turks and Bulgars.

Montenegro ought to be given a chance to decide its own future, perhaps by plebiscite. Its independence would mark the final reduction of Yugoslavia to Serbia. And this brings up the question of the Serbs in Bosnia.

The Dayton agreement is not working politically. As compensation for giving up most of Kosovo, Serbia should be permitted to co-opt the so-called Republika Srpska in a loose confederation, as provided for in the Dayton principles. Similarly, the Croatian parts of Bosnia ought to have a chance to rejoin Croatia if that is the will of the population. This, too, is a principle of Dayton.

All of Europe, including Russia, would have to guarantee any settlement. The guarantees should be a deterrence against other ethnic minorities starting a guerrilla war, for example, in Romania or Hungary.

Sanctions would have to be lifted. Probably an area-wide amnesty for war crimes would have to be declared, unpalatable as that might be. Major economic assistance should be offered. U.S. forces could be withdrawn from the area by a date certain and replaced, but not by UN forces. The peacekeepers should be drawn from all European countries, serving under a political command subordinate to a council of the Organization for Security and Cooperation in Europe.

Obviously, such a conference should be preceded by a cease-fire, including a bombing pause. But that is a dangerous move; a bombing pause ought to be part of the bargaining, not its starting point.

In 1878, the powers imposed a solution on the so-called Eastern question. Some of it was negotiated in secret, which would not be a bad precedent for this crisis, rather than reviving the sterile spotlight diplomacy of Rambouillet.

The Congress of Berlin's solution was by no means perfect, but it avoided the threat of major war and provided for several decades of peace.

The writer, a former editor of Foreign Affairs who served in the Nixon and Ford administrations, contributed this comment to The Washington Post.