UNITED NATIONS, N.Y. — THE world's major powers have been working hard to close a split in their own ranks as they decide on the best next step to end the war in Bosnia-Herzegovina.
The testing ground for whether they can hold to a united approach has shifted from Berlin to New York. Officials of the ''contact group'' that drafted the peace plan, accepted by Bosnia's Muslims and Croats but rejected by Bosnian Serbs, agreed at talks in Germany this week to ask the United Nations Security Council to ease economic sanctions on Serbia and Montenegro if the rump Yugoslav union agrees to international monitoring of its embargo against the Bosnian Serbs.
The aim is to recognize the importance of Serbian President Slobodan Milosevic's Aug. 4 decision to cut off all supplies except humanitarian aid to Bosnian Serbs. His stated plan was to punish them for rejecting the contact group peace plan. He also clearly hoped to gain relief from punishing UN sanctions against Yugoslavia. (Bosnian Army woes, page 3.)
Russia, which has close ties with the Serbs, has been the most vigorous advocate of easing UN sanctions on Serbia and Montenegro. ''There is definitely strong Russian pressure,'' says one Western diplomat close to the talks.
Yet many nonaligned nations, longtime supporters of Bosnia's Muslim-led government, as well as Britain and the United States remain skeptical of the motives and effectiveness of Mr. Milosevic's new embargo. Bosnia's Ambassador to the UN Muhamed Sacirbey contends that trucks, personnel, and other supplies move from Serbia into Bosnia at night on an almost daily basis.
The key question is whether Milosevic, in exchange for the UN's allowance of some commercial flights into Belgrade and renewed sports and cultural ties with other nations, will agree to the posting of civilian observers along the Serb border to monitor the effectiveness of his blockade.
So far Milosevic has refused. Yet many diplomats say the issue is a matter of timing and Serb pride and eventually he will agree to the monitors. ''Verification is the Council's sine qua non for any partial lifting of the embargo,'' insists one European diplomat.
THE Council's options on Bosnia have been narrowing as friction among member nations has been expanding. The contact group -- made up of the US, Russia, Britain, France, and Germany -- originally vowed to press for tighter sanctions if Bosnian Serbs rejected its peace plan. But the Milosevic blockade of fellow Serbs and Russian opposition effectively quashed that effort.
Yet President Clinton's Aug. 11 pledge to Congress to press for a Bosnian exemption to the Yugoslav arms embargo (if Bosnian Serbs do not accept the peace plan by Oct. 15) remains on the table. The Bosnian government has long argued that the move is a matter of self-defense. Yet the proposal is viewed as even more divisive for the Council than it was some months ago. Moscow has made it very clear in recent private messages to the US that it would never support such a move. Britain and France, which supply the bulk of UN peacekeeping troops in Bosnia, have long threatened to withdraw if the arms embargo is lifted for Bosnia. Russia now also threatens to pull out its troops.
For now, the five-nation contact group is making no move to change its proposed Bosnian map and peace plan. German Foreign Minister Klaus Kinkel has said a way must be found to ''bring the Bosnian Serbs on board.''
''They must change their mind and the peace plan of the contact group must be accepted,'' Russian Deputy Foreign Minister Vitaly Churkin told reporters at the close of the Berlin talks.
Could easing economic sanctions on Serbia to encourage Milosevic's continued blockade of Bosnian Serbs and their further isolation be the tool that does the job?
''I think it could force the Bosnian Serbs to come back to the table in a reasonable fashion,'' comments John Lampe, an Eastern Europe expert at the Woodrow Wilson International Center for Scholars in Washington. He argues that the map could be adjusted to the advantage of both the Bosnian government and Bosnian Serbs in offering more consolidated holdings.
Whatever the eventual outcome on the peace plan, Bosnia's Ambassador Sacirbey argues that his government has been paying the price of efforts to mask frictions in the contact group and the Council by delays in needed action. ''Any sort of open division between the Russians and the Americans seems to be something everyone is trying to avoid, but they're avoiding it at our expense,'' he says. ''We seem to be all now just buying for time.''