THE violent collision between Bosnian Serbs and international forces has brought their mission in Bosnia to a strategic crisis, UN peacekeepers believe.
Even before the crisis erupted last week, there was growing recognition that the humanitarian tasks set for the United Nations Protection Force (UNPROFOR) in Bosnia were increasingly out of tune with the military challenges and the political will of the governments that sent them here.
A review of UNPROFOR's mandate was already under way at the Security Council and among members of the ''contact group,'' made up of France, Britain, the US, Germany, and Russia. UNPROFOR officials on the ground in Bosnia hope the current crisis will at least produce a more workable framework for the peacekeeping mission.
At least 330 UN personnel are under threat at Serb hands in one way or another. Most clearly in the firing line were about 20 UN military observers who were shown on Bosnian Serb television shackled, Baghdad-style, to various potential NATO strike targets.
Faced with the blunt Serb threat to kill hostages if bombing continued, the UN suspended its call for NATO action until its political sponsors decide to go further down a road that would almost certainly involve casualties.
''Apart from backing down and negotiating, the only other option is to escalate the situation and try to get a political settlement,'' says UNPROFOR political spokesman Alexander Ivanko. ''But to do so, there has to be 100 percent backing by the international community, by the troop-contributing nations, and by the national capitals.
''We cannot put at risk their soldiers without them saying they are willing to take casualties,'' he adds.
So the world powers were again thrown into disarray by Bosnian Serb defiance. UNPROFOR command on the ground and its political sponsors are trying to decide how to proceed -- and who should take responsibility for the consequences.
As world capitals agonized over how to deal with the crisis, the Bosnian Serbs themselves appeared to have no doubts about their defiant course of action. ''It's simple for the Serbs -- they're a people at war, while we're a gaggle of different nations brought together for a peacekeeping mission in a country with precious little peace to keep,'' says one UNPROFOR official.
While officials are unwilling to try to predict how the crisis will fall out, UNPROFOR's operational presence in the Serb-controlled areas has effectively been liquidated. Physically if not politically, they have been obliged by force of circumstance to take sides, and have themselves become embroiled in conflict with one party to the Bosnian war.
The British decision to send in reinforcements to help defend their own peacekeeping contingent raised the prospect of peacekeepers using heavy artillery to defend their own presence -- a far cry from the vision that underlay the original UNPROFOR mission. Until they arrive, UN peacekeepers on the ground have no option but to keep their heads down and try to stay alive.
''We had peacekeepers out there in isolated and exposed positions, and people kept calling on us to use force,'' says UNPROFOR military spokesman Lt. Col. Gary Coward, highlighting the dilemma of vulnerable peacekeepers expected to enforce the ''total exclusion zone'' (TEZ) around Sarajevo when the warring parties were bent on going back to war.
''This crisis has brought to a head all the inherent contradictions of this mission,'' he adds.
Given those contradictions, it was a crisis waiting to happen. British Lt. Gen. Michael Rose, who commanded UNPROFOR in Bosnia when the TEZ was imposed by the UN and NATO in the spring of last year, always said privately that its maintenance depended on a bluff that would erode without a peace settlement.
That bluff was finally called by the Bosnian Serbs last week. Following the April expiration of the four-month cease-fire negotiated by former President Jimmy Carter, clashes between mainly Muslim government troops and the Bosnian Serbs broke out with mounting frequency and intensity in various parts of the country, and around Sarajevo, one of the six UN-designated ''safe areas.''
On May 7, the current UNPROFOR commander, Lt. Gen. Rupert Smith, believed the threshhold for international intervention had been reached when a Serb mortar killed 11 civilians in the Muslim suburb of Butmir in Sarajevo.
But his request for the use of NATO air power to punish and deter the Serbs was not approved by the other two men who have to turn the operational keys -- the overall UN force commander in the former Yugoslavia, Lt. Gen. Bernard Janvier, and the senior UN political official in Zagreb, Yasushi Akashi, who apparently feared it might upset the situation in neighboring Croatia.
When the Serbs initiated battles in and around Sarajevo in the second half of May, it was only a matter of time before UNPROFOR had to call in NATO air power if there was to be any chance of salvaging the TEZ's violated integrity, and UNPROFOR's own much-impugned credibility.
''With both sides firing dozens of heavy weapons inside the zone, and the situation rapidly getting out of hand, we simply had no other option but to call for NATO airstrikes,'' says UNPROFOR's political spokesman Alexander Ivanko.
The decision was made in full awareness that UN peacekeepers manning weapons collection points or acting as military observers were at risk. During past crises, the Serbs had theatened some of them. So their actions now came as no surprise.