WITH Bosnian Muslims and Croats poised to sign a peace accord, Serbs are under mounting pressure to talk peace in Bosnia-Herzegovina.
The still-undisclosed United States-brokered peace pact, to be signed by March 18 at the White House, includes a constitution for a federation of Swiss-style cantons that could eventually establish links with Croatia.
The two sides agreed on March 12 to merge their forces, and they have also settled the principles by which the cantons will be drawn.
While US mediators authored the Muslim-Croat accord, they have pressed no specific plans on the Bosnian Serbs and their patron, President Slobodan Milosevic of Serbia.
This appears to be a deliberate tactic designed to make Mr. Milosevic and Bosnian Serb leader Radovan Karadzic directly responsible for the fate of what many believe is a last-chance effort to end the war.
``This is a fast-track process,'' explains a senior Western diplomat. ``We are not in this thing for an interminable series of negotiations. Now, it is up to the Serbs to decide whether they are going to take advantage of this vanishing opportunity and to make the necessary concessions.''
US, Croatian, and Bosnian officials decline to disclose the consequences the Bosnian Serbs would face should they refuse to negotiate and instead press their plans for territorial expansion.
But diplomats indicate the West remains resolved to use air power against the Bosnian Serbs to enforce UN resolutions. And implicit in the Muslim-Croat reconciliation, they say, is the potential for a renewed military alliance against the Bosnian Serbs, only this time silently sanctioned and supported by the West.
``If they [the Bosnian Serbs] continue to be very aggressive militarily,'' the senior Western diplomat warns, ``they run into the possibility of military strikes and into renewed efforts to lift the [UN] arms embargo.''
But the rewards for cooperating will be a gradual lifting of the devastating United Nations sanctions imposed on Belgrade and the prospect for the economic aid Messrs. Milosevic and Karadzic desperately require for reconstruction and political stability.
US and Croatian officials are counting that Milosevic and Karadzic can be lured into bargaining in good faith.
``If they don't, they lose the opportunity for peace, they lose the opportunity to consolidate what they might realistically hold,'' the senior Western diplomat says. ``And Serbia and the Bosnian Serbs face greater isolation than they do now.''
Western diplomats say the Bosnian Serbs can opt to join the Muslim-Croat federation or create their own political entity that would maintain loose links with the other. Or they can propose their own arrangement to end the 23 month-old conflict.
The diplomats and Croatian officials also stress that the idea of tying the Muslim-Croat federation to Croatia could easily be dropped if the Bosnian Serbs demand that they be allowed to confederate with Serbia-controlled rump Yugoslavia.
``We do not insist on any particular relationship between Bosnia and Croatia,'' says Croatian Assistant Foreign Minister Tomislav Bosnijak. ``The confederal arrangement is something that is possible, but has not been set in concrete.''
One thing Zagreb will never accept is an arrangement in which the Muslim-Croat federation is linked with Croatia and the Bosnian Serbs tied to Serbia.
That, Mr. Bosnijak says, sounds too much like a revival of former Yugoslavia, from which Croatia seceded in June 1991.
In opting to cooperate, Milosevic and Karadzic face tough choices. The Bosnian Serbs will have to relinquish some 20 percent of the 70 percent of Bosnia they seized in their ethnic cleansing conquests ignited by the republic's secession in 1992.
They would also have to remain inside Bosnia's recognized borders and forget their goal of unifying in a ``Greater Serbia'' with Serbia, Montenegro, and Croatia's Krajina region, which was overrun in 1991 by Milosevic-backed Serbian rebels.
The Krajina, meanwhile, will have to be reincorporated with Croatia, with its minority Serbs given extensive autonomy.
Skeptics emphasize that it is over these very points that previous European and UN peace-making initiatives collapsed. But Russia, in its new ``good cop'' role as chief intermediary with Belgrade and the Bosnian Serbs, now appears to have brought its diplomatic muscle to bear.
``The thing that I encourage them [the Serbs] to do is to keep thinking in terms of the territorial integrity of Bosnia,'' special Russian envoy Vitaly Churkin said in Belgrade on March 14.
There have been mixed signals from Belgrade and the Bosnian Serb leadership, which must deal with powerful hard-liners opposed to any concessions.
Karadzic says he is willing to discuss joining the Muslim-Croat federation if the Bosnian Serbs can have close links with Serbia.
Other senior Bosnian Serb leaders have expressed a willingness to negotiate and insist they want peace, citing their withdrawal of heavy artillery earlier this month from around Sarajevo and the success of a UN-monitored cease-fire there.
But they are unwilling to commit to specific concessions and remain vague as to what territories they might be willing to relinquish as part of a peace deal.
Meanwhile, the Serbs continue offensives and artillery barrages against the besieged northern Bosnian government-held enclaves of Maglaj and Bihac.