While Secretary of Defense William Cohen is unlikely to have put it in quite these terms, he has begun asking similar questions about NATO’s 36,000 troops in Bosnia. It’s about time.

In 1995 President Clinton announced that he was sending the United States military to Bosnia on a mission ““precisely defined with clear realistic goals’’ that could be achieved within a year. In 1996 the president extended the Bosnia mission by 18 months. In recent weeks, both Secretary of State Madeleine Albright and national-security adviser Sandy Berger have suggested that the American military presence might have to be extended even longer. ““Peace is beginning to take root,’’ Berger said. ““The gains are not irreversible, and locking them in will require that the international community stay engaged in Bosnia in some fashion for a good while to come.’’ Less important than the shifting date is the extravagant and unrealistic mission. America’s goal is now, as Berger explained on Sept. 23, ““to achieve a unified, peaceful Bosnia, restore basic freedoms [and] put a broken economy back on its feet.’’ Hmm. The troops had better get ready for a long stay.

““A unified, peaceful Bosnia’’ is a contradiction. You can have a unified Bosnia or a peaceful Bosnia, but not both. Everything that has happened in the past six years suggests that powerful forces for ethnic separatism exist in that country. They may or may not constitute a majority, but they are popular and powerful enough to have dominated Bosnia’s politics since the collapse of Yugoslavia, and they are likely to do so in the future.

From the moment Yugoslavia began to falter, these forces–mainly Serb and Croat–attempted to secede from a multiethnic Bosnia. When they could not do so peacefully, they began a war, raping, killing and maiming their ““countrymen.’’ Large populations of Serbs, Muslims and Croats have moved–usually at the point of a gun–so that Bosnia is now ““ethnically cleansed’’ into distinct enclaves. Despite the Dayton accord’s specific requirement that populations be allowed to return to their homes, almost none have actually done so. In virtually every election held during the past five years, ethnic separatists have won. ““There is one issue in this election: whether you are Serb, Croat or Muslim,’’ says Chris Bennett of the International Crisis Group, who observed the last Bosnian elections. Even the Bosnian Muslims, the sorriest victims in this tragedy, have been radicalized and now are understandably wary of living in one country side by side with Serbs.

Bosnia exists as a unified and peaceful country today because of the presence of NATO troops and what they symbolize–the West’s military power. This mirrors an older pattern. Bosnia’s multiethnic character has always required that it be ruled by a foreign entity, giving ultimate authority to a distant nation rather than one of its own three ethnic factions. In the past it was the Ottoman or Hapsburg empire–the Croats would rather be ruled by Vien- na than Sarajevo. Today it is NATO, but the principle is the same. And when the foreign power has withdrawn or crumbled–as Yugoslavia did in 1991–questions of political power return to Bosnia, and conflict resumes.

When NATO leaves and the Bosnians have to decide for themselves once again who exactly will rule whom, they will struggle again. The current battle between Radovan Karadzic and Biljana Plavsic for the presidency of the Bosnian Serbs is indicative of the contests we can look forward to, pitting as it does a highly corrupt Serb nationalist against a slightly corrupt Serb nationalist. Does anyone at the Pentagon or in the White House honestly believe that Plavsic–whom they support, and who has a long record of hatred toward both Muslims and Croats–sincerely wants to create a multiethnic Bosnia?

Nonetheless, the administration argues, American credibility is on the line. Credibility is the last refuge of bad foreign policy. Whenever a particular intervention cannot be defended on its own terms, politicians make vague claims about the threat to American credibility. (““If we don’t stand firm here, we will not be able to deter rogue nations anywhere!’’ Never mind that when we do punish aggressors in one corner of the world–Iraq–it doesn’t seem to deter things in other places. Maybe they understand something we don’t: that deterrence is nontransferable.) American credibility is threatened only because the adminis- tration has intervened in this complicated conflict without, to use Clinton’s own formulation, ““precisely defined and clear realistic goals.’’ Now the administration will have to get some–like watering down Dayton’s requirement and accepting a de facto partition, perhaps while maintaining the fig leaf of one country. If it doesn’t, extending the mission will not shore up American credibility. And in today’s politically correct climate, the troops in Bosnia don’t even have the option of chasing girls.