WASHINGTON -- President Clinton, voicing fear that the Balkan war could widen and destabilize Europe, tried to put his campaign for military pressure against Bosnian Serbs back on track yesterday amid signs that it may have faltered beyond repair.
After a four-day world preoccupation with a peace that never came, the president instructed Secretary of State Warren M. Christopher, in his remaining meetings with European leaders, to focus solely on more effective action against the Serbs.
Mr. Christopher's trek to line up a concerted allied stand had been partly derailed by planning for a peacekeeping force in the hope that the Serbs might be ready to halt their aggression in Bosnia.
The administration switched gears yesterday after the Bosnian Serb parliament effectively rejected a peace plan mediated by Europe's Lord Owen and Cyrus R. Vance of the United Nations. The plan had been conditionally signed Sunday by the Serb leader, Radovan Karadzic.
The Serbs' decision shattered growing expectations that a NATO-dominated, 70,000-troop peacekeeping force might be sent into Bosnia soon to oversee an end to the year-old war that has brought Europe its worst atrocities since World War II.
But there were no signs yesterday of a stepped-up timetable for U.S. and allied military action. Administration officials continued to say that any final decision would await Secretary Christopher's return tonight and that action had to be in concert with allies.
Diplomats predicted that such action probably would not come before sometime next week. On Capitol Hill, there was some belief that Mr. Clinton, with allied acquiescence, might move ahead with air strikes against Serbian positions near Sarajevo and in eastern Bosnia without first seeking a formal congressional vote, despite a growing call for lawmakers' approval beforehand.
In closed briefings on Capitol Hill yesterday, Gen. Colin L. Powell, chairman of the Joint Chiefs of Staff, outlined options of air strikes on Serbian targets in Bosnia and also military targets or electrical power sites in Serbia proper, according to Rep. Dave ,, McCurdy, an Oklahoma Democrat.
But the congressman drew from the general's briefing "a forewarning to people not to have great expectations" about the effectiveness of the strikes in ending the war.
Nevetheless, Mr. McCurdy said, the United States has put its own credibility on the line to such an extent in raising expectations about force that "if we back down now it creates even greater problems."
Mr. Clinton called yesterday's Serbian vote "a grave disappointment," despite the administration's own warnings Saturday that Serbs had to prove their peace commitment with a halt to shelling and other actions that failed to materialize.
"There was the hope among a number of people, including ourselves, that we would not be faced with the situation we are today," an administration official said. "Clearly we were looking at one track over the last three or four days. Clearly that has become less likely."
Mr. Christopher voiced the same view during his visit to Bonn, Germany: "The focus now will be solely on what we might do to devise some more effective actions to take against the Bosnian Serbs. Until today we were basically discussing two different tracks. Now, we're focusing on a single track."
In renewing the secretary's original mission, Mr. Clinton betrayed some impatience with European allies who have done little to hide their lack of enthusiasm for use of force, particularly a lifting of the United Nations arms embargo on Bosnian Muslims, who are severely outgunned by the Serbian forces.
"The vote last night simply makes this Christopher mission more important," Mr. Clinton said in a prepared statement topping a speech yesterday at the Export-Import Bank here.
"Secretary Christopher will be insistent that the time is come for the international community to unite and to act quickly and decisively. America has made its position clear and is ready to do its part. But Europe must be willing to act with us. We must go forward together."
But the president's new forcefulness was not matched by statements of similar strength in allied capitals Mr. Christopher has visited.
In London, a senior Foreign Office official said the Vance-Owen plan offers "the best chance for a lasting peace in Bosnia." He called on Serbian President Slobodan Milosevic and others to "redouble efforts to persuade the Bosnian Serbs that the only way forward to a better future is acceptance of this plan and full cooperation in its implementation.
"The government have made clear that we do not rule out other options. We shall continue consultations with our partners and allies on such measures," according to his statement.
Mr. Clinton spoke by telephone with French President Francois Mitterrand for 20 minutes, but their conversation focused mostly on the current situation and the two reached no conclusion on future actions, an administration official said.
Within the administration, there is concern about "what the Bosnian Serbs are planning, what will go on over the next week or so," the official said.
The administration took a wait-and-see attitude toward Serbia's decision to punish Bosnian Serbs with a partial sealing of the border, a move that reinforced Lord Owen's belief that a true policy shift had occurred in Belgrade.
"We'll see whether that works. We've heard things like that before," the official said.
In his speech at the Export-Import Bank, Mr. Clinton gave his most complete account of the stakes in the former Yugoslavia for the United States.
"The Serbs' actions over the past year violate the principle that internationally recognized borders must not be violated or altered by aggression from without," Mr. Clinton said.
"Their actions threaten to widen the conflict and foster instability in other parts of Europe in ways that could be exceedingly damaging. And their savage and cynical ethnic cleansing offends the world's conscience and our standards of behavior."
On Capitol Hill, Senate Armed Services Committee Chairman Sam Nunn, a Georgia Democrat, just back from a trip to the Balkans and Russia, called for existing United Nations forces in Bosnia to be restructured under military, rather than humanitarian, leadership, and equipped with heavier weaponry.
WHAT'S WHAT IN YUGOSLAVIA
Yugoslavia: Used to consist of six republics: Serbia, Croatia, Slovenia, Montenegro, Bosnia-Herzegovina and Macedonia. Since the breakup of Yugoslavia in June 1991, the rump state has consisted of Serbia and Montenegro.
The rump Yugoslavia has a president, Dobrica Cosic. The president of Serbia is Slobodan Milosevic.
Serbs: These are the predominantly Christian Orthodox inhabitants of Serbia.
Bosnian Serbs: Inhabitants of Bosnia who are of Serbian ethnic origin and who want to annex themselves to Serbia. Heavily armed by Serbia, they have taken over 70 percent of Bosnia in the past year.
Other Serbs: Serbs also live in portions of Croatia that they wish to annex to Serbia. Fighting similar to that in Bosnia occurred in Croatia. Thousands died, and Serbian forces still hold large parts of Croatia.