UN Mission Mired at Crossroads As Serbs Advance on Muslims

THE fall of the Bosnian city of Srebrenica to Serb forces July 11 raises the question whether a United Nations presence now can serve any purpose in resolving this conflict.

The two-day Serb offensive toppled the first of six UN-guaranteed ''safe zones,'' leaving roughly 20,000 Muslim residents in flight, along with some 400 Dutch peacekeepers. Thirty Dutch soldiers remain behind as hostages. NATO forces responded with two air attacks. But Serb leaders threatened to shell fleeing civilians if attacks continued.

Western European powers, concerned about casualties to the UN peacekeepers, are divided about what strategy to take in face of this most recent Serb attack. France has called for a UN-directed military intervention to win back the city, while Britain has yet to commit.

''If we don't reestablish the enclave of Srebrenica, there's nothing to stop the Serbs from taking over other Muslim enclaves, including Sarajevo,'' President Jacques Chirac said in Strasbourg, France.

But British partners, who joined France in supporting the creation of a UN Rapid Reaction Force (RRF), were less forthcoming. ''We share [Mr. Chirac's] objective, but we have to consider how best to achieve this,'' said a spokesman for the British Foreign Office yesterday. ''We still favor a diplomatic resolution of the crisis.''

But even if France and Britain could agree on a beefed-up deployment of forces, UN officials doubt the viability of their mission. ''The reaction force is some 250 kilometers [155 miles] away, across difficult terrain,'' says French Cmdr. Guy Vinent, a spokesman for the UN Protection Force (UNPROFOR) in Bosnia, reached by phone in Sarajevo yesterday. ''In addition, there is the problem of moving this force through a Serb zone.... It's at least curious that we can't use force without the permission of warring parties.''

The promised RRF of 12,500 troops was set up after Bosnian Serbs took some 400 UN peacekeepers hostage last month. Some 2,000 members of this force are already deployed in Bosnia. The RRF, like the 23,000-member UNPROFOR, requires UN authorization to move about the country.

''The UN gave its word to protect these zones, and has done nothing to keep it,'' says Hans Stark of the French Institute of Foreign Relations in Paris. ''This could lead to the fall of [UN-guaranteed safe zone] Zepa as well.''

''The world now needs to decide between two scenarios,'' he adds. ''A UN withdrawal now appears inevitable. If there is no lifting of the arms embargo, there will be an overwhelming victory by the Serbs. If the embargo is lifted, there is a risk of expanding and internationalizing the war, but the Muslims can be saved.''

On June 28, NATO approved a plan to send up to 60,000 troops to Bosnia, if an evacuation of UNPROFOR becomes necessary. ''It's a very complete scenario,'' says one Western diplomat.

US officials, for their part, appeared surprised by the swift fall of Srebrenica. While Secretary of Defense William Perry appeared to question whether UN troops could remain in Bosnia considering the military situation, Secretary of State Warren Christopher said the UN's humanitarian tasks were still worth accomplishing.

Meanwhile, Senate majority leader Bob Dole called the UN mission a disaster. He repeated his call for a unilateral US lifting of the UN arms embargo against Bosnia ''to let the Bosnians do what the UN is unwilling to do for them.'' Analysts questioned Serb motivation in humiliating UN forces on the eve of the US congressional vote on the arms embargo.

''I think they want UNPROFOR out,'' says one Western diplomat. ''All three parties to the conflict feel confident that were the whole thing to collapse into a military conflict again, they could gain an advantage.''

UNPROFOR spokesman Vinet dismisses the upcoming US vote on the embargo. ''All the media attention was focused on Sarajevo,'' he says. ''Everyone talks about Sarajevo. Everyone thinks about Sarajevo. And in military terms, it created a window that opened.''