Major Powers Stumble After Bosnian Serbs Call Their Bluff : Balkans: Conditions on peace plan stall process. Five-nation contingent backs off on tough rhetoric.

For two weeks or so, five of the world’s strongest military powers engaged in an unprecedented show of resolve to finally bring an end to the messy war in Bosnia-Herzegovina.

Working together for the first time, Russia, the United States, Germany, Britain and France laid down terms of their peace plan and set a firm July 20 deadline for the warring parties to respond--take it or leave it. They then stressed the dire consequences that would follow if either side rejected the accord.

But Thursday, hours after Bosnian Serb leader Radovan Karadzic had met representatives of the five in Geneva and effectively called their bluff by presenting conditions to what was meant to be a “yes or no” offer, the common front of the major powers seemed to suddenly dissolve.

The earlier tough rhetoric, aimed mainly at the Bosnian Serbs, also came to a halt.

Adding to the general sense of disarray, Bosnia’s Muslim-led government Thursday withdrew the unconditional acceptance to the peace plan it had given Wednesday morning to five envoys, citing the Bosnia Serb rejection for the move.

In the aftermath of Wednesday’s meetings, only the United States seemed prepared even to admit that the Bosnian Serbs had rejected the plan. “The Bosnian Serb delegation had not accepted our territorial proposal,” U.S. envoy Charles Redman told reporters in Geneva late Wednesday night.

Redman arrived here late Thursday to confer with officials at the headquarters of the North Atlantic Treaty Organization, which could become more deeply involved in Bosnia, as part of an international effort to police an agreed settlement or to assist in carrying out some of the threats made against the Bosnian Serbs. Those measures include extending military exclusion zones in Bosnia and lifting the arms embargo against the Bosnian Muslims.

But there was little talk of such action Thursday in European capitals.

In London, a Foreign Office spokesman stressed the need for further consultation and repeatedly refused to label the Bosnian Serb response as a rejection. “Of course, things would have been easier if we’d had two yeses, but we’re still on line,” the spokesman insisted.

Under terms of the peace plan, a Muslim-Croat federation would receive 51% of Bosnia, with the Bosnian Serbs getting the remaining 49%. After almost 2 1/2 years of war, Bosnian Serbs control about 70% of the country.

The Bosnian Serbs reportedly insisted on keeping parts of the capital, Sarajevo, want access to the sea and want to keep a corridor in northern Bosnia linking Serb-held areas with Serbia.

In a statement issued in Bonn, German Foreign Minister Klaus Kinkel labeled the Serbian answer “disappointing” but then seemed to extend the deadline 10 days, until a scheduled foreign ministers meeting in Geneva on July 30 considers the next step in the crisis.

Russian Foreign Minister Andrei V. Kozyrev described the Bosnian Serb demands for more information as “legitimate,” and Thursday officials in Moscow seemed to echo calls to delay any response.

“Let me repeat that we consider it important that the reaction of the Bosnian parties should be presented by the contact group to the ministers before the ministers pronounce their final verdict,” said Mikhail Demurin, deputy spokesman for the Russian Foreign Ministry.

While he admitted there seemed little reason to consider lifting international sanctions against Serbia--a key enticement for Serbs to accept the peace plan--he also seemed to put in doubt Russian support for moves to end the arms embargo against the Bosnian Muslims in case of a Serb rejection. “This should be done only on the decision of the international community as a whole, the United Nations as a whole, and unilateral moves would only undermine the international legal regime, this would be utterly wrong,” he said.

Lifting the arms embargo is the most controversial, severe measure envisioned to force Bosnian Serbs to accept the peace plan.

But such cautiously worded responses immediately rekindled doubts about the political will of the five powers to follow through with their threatened measures against the Bosnian Serbs.

“We are seeing another classic case of prevarication,” said Jonathan Eyal, director of studies at the Royal United Services Institute, a London-based military think tank. “The bottom line is that the West hopes the war will simply go away. This plan has no more chance of success than any of the others.”

Eyal and other observers fear that the Bosnian Serbs may have probed the unique--and weakest--element of this peace plan: the five major powers’ solidarity.

Russia has strong religious and cultural ties to the Serbs; Germany is equally bound to the Croats; Britain, France and the United States tend to differ on issues, such as the lifting of the arms embargo against the Muslim-led Bosnian government.

Meanwhile, the humanitarian airlift into Sarajevo was suspended for the second time in 24 hours Thursday as groundfire hit three separate aircraft, including two U.S. Air Force planes carrying relief supplies into the Bosnian capital from their home base in Frankfurt, Germany.

Beth Knobel of The Times’ Moscow Bureau contributed to this report.