THE Yugoslav civil war has entered a decisive phase with the end of United Nations mediator Cyrus Vance's latest mission. The main protagonists face the choice of embracing his plan for peacekeeping forces or facing unabated violence.
"I think they all understand that the Vance mission is the last chance they have, that a failure of the Vance mission could result in a major escalation of the war" says a Western diplomat here.
Mr. Vance has for now ruled out the deployment of UN peacekeepers because fighting between Serbs and Croats has continued in disregard of a Nov. 23 cease-fire accord; the accord's implementation is the main condition for UN Security Council approval of the plan.
But the plan remains the only option for halting the savage five-month-old conflict, and despite the failure of Vance's exhaustive attempts to secure the cease-fire, the UN is expected to pursue its peace efforts.
The fate of the cease-fire now rests firmly with separatist Croatian President Franjo Tudjman, Communist President Slobodan Milosevic of the rival Serbian Republic, and Yugoslav Defense Minister Veljko Kadijevic, the most senior general of the Serb-dominated federal Army.
Western diplomats and other analysts said all three have indicated they might be willing to cooperate to solidify the cease-fire, because of growing public weariness of the war and worsening economic conditions wrought by international sanctions.
One indication is Vance's surprise disclosure on Sunday that he had obtained the "substantial agreement of the principal parties" to a "concept and underlying plan for a possible peacekeeping operation."
Though the former US secretary of state declined to elaborate on the scheme, his announcement indicated that he had persuaded Mr. Milosevic and General Kadijevic to relent in their opposition to stationing UN troops in Croatia's Serbian enclaves.
Both had insisted that UN troops be deployed only in buffer positions on the boundaries of those enclaves, which would have de facto accomplished their goal of ensuring that territories wrested by force remain severed from Croatian authority.
Mr. Tudjman recognized that earlier this month when he agreed to allow the stationing of international peacekeepers in all crisis areas, dropping a demand that they be positioned only on Croatia's borders with Serbia and the republic of Bosnia-Herzegovina.
A second bright spot was an accord that Vance's deputy, former US Ambassador Herbert Okun, helped broker between Croatia and the Yugoslav Army to complete the removal of blockades on three military facilities in the republic's capital of Zagreb.
The Serbian military high command has been adamant that Croatia lift all the sieges that it imposed in mid-September.
Western diplomats have blamed Croatia's foot-dragging for the Army's violations of the Nov. 23 cease-fire, including bombardments that claimed more than 100 …