LONDON -- Bosnian Serb leader Radovan Karadzic agreed to an international peace plan yesterday to end a year of ethnic carnage, but a skeptical United States pushed ahead in lining up a military coalition to intervene in the Balkans.
With the threat of Western air power looming and pressure from Serbia, Mr. Karadzic signed on in Athens, Greece, to the peace plan, which requires the Serbs to give back land to outgunned Muslims and Croats and carves Bosnia into 10 semiautonomous regions.
The plan must now be approved by the self-proclaimed Bosnian Serb parliament. It already has rejected the peace deal twice, and the parliament speaker quickly expressed his disapproval yesterday. The accord "is not acceptable as it is now," said Momcilo Krajisnik, casting a shadow over any hope for approval. A vote is expected later this week.
Mindful of the many broken cease-fires in Bosnia and the hard-liners in the Bosnian Serb parliament, Secretary of State Warren M. Christopher gave no hint that his consultations on military options will be modified this week.
Mr. Christopher was here on his first stop in a six-day tour through Western Europe and Russia. His mission is to gather allied support for what he described as "a number of recommendations, including military steps."
"The secretary considers the announcement in Athens good news," the State Department said early yesterday. "But . . . it will take more than a signature on a peace plan to convince the international community that the Bosnian Serbs are serious and acting in good faith. It will take deeds and concrete actions."
The same skepticism was evident among the British. A senior government official said: "Signing a piece of paper is one thing, but implementing it is another. We need to keep up the pressure."
In Washington later, President Clinton also took the development in Greece with a grain of salt, describing it as "a positive step," but adding, "We have yet to determine whether the Serbs are serious about peace."
He ordered his secretary of state to proceed with his mission. Congressional leaders who were briefed by Mr. Clinton confirmed that the measures that Mr. Christopher is carrying include air strikes against Serbian military positions in Bosnia and a lifting of the arms embargo to aid Bosnia's Muslims.
But in Vouliagmeni, a resort town 12 miles south of Athens and the site of the weekend peace talks, the mood was more optimistic.
"This is a happy day for the Balkans," declared Lord Owen, the European Community's peace negotiator. He described Mr. Karadzic's signing of the peace plan, devised by himself and Cyrus R. Vance, representing the United Nations, as "a commitment."
They had moved, he said, "within a very close distance now of a very comprehensive peace settlement."
The Vance-Owen plan would divide Bosnia into 10 semiautonomous regions, each occupied mainly by Muslims, Croats or Serbs. The plan had already been signed by the Muslims and Croats but was rejected by the Bosnian Serb assembly.
The assembly will take it up again Wednesday.
There were no details given in Greece on whether concessions -- such as corridors linking Serb-held territories in Bosnia -- had been agreed upon.
Lord Owen gave most of the credit for the collapse of Mr. Karadzic's resistance to signing the plan to the Serbian president, Slobodan Milosevic, "the person I have always believed would ultimately deliver a settlement."
He dismissed the significance of the Bosnian Serb assembly vote, saying that even if it does reject it again, "I think the commitment of the Yugoslav government now to the peace settlement is total and they will deliver it, even if there were to be problems with the assembly."
Mr. Christopher met last night with Prime Minister John Major, Foreign Secretary Douglas Hurd and Defense Secretary Malcolm Rifkind. They were prepared to offer strong opposition should the secretary propose, as was expected, lifting the arms embargo for the Bosnian Muslims.
This, a high British official said last week, makes the government "incredibly nervous." The feeling here and in France is that such a move would not aid the Bosnians so much as heat up the war, possibly drag in countries on the periphery of it, such as Greece and Turkey, and involve allied troops directly in the hostilities.
Over recent weeks Britain and France have grown more accepting of the other option widely discussed in Europe and the United States -- air strikes against the Bosnian Serbs. But neither country favors them, nor do most European military leaders. As a strategy they are seen as a lesser evil than lifting the arms ban.
Britain and France are the two largest contributors of troops to the U.N. humanitarian mission in Bosnia, with about 2,500 and 5,000 respectively. Both have sustained casualties and expect that those casualties would grow should air strikes begin and the Bosnian Serbs begin to retaliate.
Also, both countries expect that bombing would bring to an end the United Nations' humanitarian efforts in Bosnia.
Britain, France and other European countries support the continued isolation of Serbia and application of economic sanctions ever more tightly as a way to bring pressure on the Bosnian Serbs.
The "breakthrough" toward peace in Greece yesterday, if indeed it proves to be that, could be a sign that policy is starting to work. Yesterday was the first time Mr. Karadzic agreed to sign the Vance-Owen plan, and it was believed by many, in addition to Lord Owen, that he caved in to pressure exerted by President Milosevic.
Mr. Milosevic is widely thought to have instigated the Bosnian war in his quest to carve out of the former territory of Yugoslavia a "Greater Serbia" at the expense of his neighbors. Up to now he has been the principal supporter of the Serbs in Bosnia. But new U.N. sanctions went into effect against Serbia and its ally Montenegro last week, promising an even greater strain on an already dying economy.
Serbia is wracked by business failures, falling production, unemployment and hyperinflation. Serbs cannot sell their goods abroad or import anything that would help the economy. Planes don't fly there. Gasoline is in scant supply. The brightest and best educated Serbs are emigrating.
All this has been wrought by the sanctions in effect before last week's took effect. The new sanctions will make things even worse.
Also, the threat of military action by the allies against the Serbs in Bosnia, with the possibility that the Yugoslav National Army might also be attacked or drawn into the fighting in defense of the Bosnian Serbs, is thought to have caused Mr. Milosevic to rethink his expansionist policies and, at least for the time being, made him more amenable to the idea
of peace in Bosnia.
Whether he can extend his influence to a majority in the Bosnian Serb assembly Wednesday, and then to a majority of Bosnian Serbs when they vote on the Vance-Owen plan in a referendum May 15, is uncertain.
Mr. Christopher was to fly to Paris from here. He will also visit Germany and Russia and meet the leaders or high officials of Spain, Greece, Italy, the Netherlands and Turkey.
Accompanying him is Reginald Bartholomew, President Clinton's envoy appointed to deal with former Yugoslavia.