PARIS. — Paris -- The present Serbian government's program to make a ''greater'' Serbia, incorporating large parts of Bosnia-Herzegovina as well as of Croatia, seems on its way to success. There is no one to stop it.
The Serbian-dominated ex-federal army is the principal military force in the region, possessing heavy weapons. The newly arrived U.N. peacekeeping force and the European Community's observers are being brushed aside. Neither have the means nor the mission to fight Serbia.
The Serbs' reward will be a big and economically crippled Serbian-Montenegrin union, facing the prospect of insurrection by the 1.2 million Albanians of Kosovo, whom the Serb authorities now dominate and oppress. It will be surrounded by pillaged neighbors, their hatred of Serbia recklessly reawakened, awaiting revenge.
This new state will be isolated internationally. It already suffers economic and diplomatic sanctions imposed by all the democracies. It will be deprived of all successor-rights pertaining to the former state of Yugoslavia. It will have squandered the sympathies of the Allied powers of both world wars, once Serbia's allies.
What an achievement for Slobodan Milosevic and his government -- who told their fellow Serbs that ''with us there is no uncertainty''! There is none indeed: This victory for Serbian irredentism and expansionism is prologue to a national catastrophe.
When Washington took the initiative last week to propose
Serbia's expulsion from the CSCE -- the group dealing with security and cooperation in Europe -- if Serbia's aggression does not halt, it was an overdue change in U.S. policy, although Washington's reluctance until now to take such a step is comprehensible. U.S. Ambassador Warren Zimmermann and the Department of State kept up their dialogue with the Milosevic government in the belief that they might save Serbia and its neighbors from the catastrophe Lebanon has undergone.
America's leaving the diplomatic lead with the European Community until now was also a sensible policy, given the nature of the affair and the West Europeans' past claims to a share in international leadership. In practice it unfortunately demonstrated the European Community's incapacity to conduct a common foreign policy on any matter where the European governments have divergent views and where public opinion is divided. This was the case on initial recognition of the breakaway Yugoslav republics of Slovenia and Croatia, and then on the question of intervention.
Europe's failure combined with American diffidence to embolden the Serbian leadership and feed their illusion that the European nations and the United States are once more divided by power rivalries and aggressive ambitions. (''France has abandoned Serbia because it fears losing Alsace-Lorraine,'' a Serbian university professor said last week, in all seriousness, to a French reporter in Sarajevo.) Thus the shock produced in Belgrade by the American change of policy, and by the support it received throughout Western Europe.
However, Washington has a historical responsibility in this affair. Yugoslavia as it existed until last year was the work of a number of 19th and early 20th century reformers among the South Slav peoples themselves, who believed that their individual nations, freed from Ottoman and Hapsburg power, should be united. Their ideas were adopted by the Americans who drafted Allied policy on Balkan political frontiers after World War I.
This informal committee of Americans was drawn from the secret policy planning group called ''The Inquiry,'' convened in October 1917 by President Woodrow Wilson. The committee worked with maps and tables of ethnic population distribution to establish borders for the new nations. It was composed of Walter Lippmann, then a young journalist; Sidney Mezes, president of the City College of New York, a philosopher of religion; David Hunter Miller, a New York lawyer; and the head of the American Geographical Society, Isaiah Bowman. Mezes was the brother-in-law of President Wilson's foreign policy adviser, Col. Edward House. Miller was the law partner of Col. House's son-in-law.
They believed in national self-determination, but also thought there should be a new democratic federation of the new nations to take the place of the Hapsburg and Ottoman systems. (This, in the event, was opposed by Thomas Masaryk, who wanted a fully independent Czechoslovakia.) The planners believed -- as the British historian A. J .P. Taylor has said -- that ''Serbs, Croats and Slovenes would merge into Yugoslavia as Prussians, Saxons and Bavarians had merged into Germany.''