"Republika Srpska", the secessionist Serb statelet in Bosnia, has a few hours to decide whether to endure the international yoke or opt for the slaughterhouse.
General Ratko Mladic received an ultimatum from Nato and the UN yesterday, warning him to pull back from the brink or face retribution of awesome proportions.
Early indications were that sense would prevail. But it has been a rough weekend for officials trying to convince the rebel Serbs in Pale to accept their fate.
The full fury of Gen Mladic, the Bosnian Serb commander, fell on the UN Force Commander, General Bernard Janvier, during a 14-hour meeting on Friday and Saturday, interrupted on several occasions as Gen Mladic stormed out. When he did stay to negotiate, he spent much of the time insulting the French general and his family.
The meeting, in Mali Zvornik, a shabby town on the Serbian side of the border with Bosnia, was set up after a phone call to the UN from President Slobodan Milosevic of Serbia on Friday. The first four hours were taken up with "the kind of psychological warfare the Serbs play well", a UN source said. Gen Mladic refused to negotiate "at the point of a gun" and demanded an end to Nato flights during the talks.
When the real talks began at 6pm, a very high-ranking Yugoslav officer spent some time explaining to Gen Mladic, in painful detail, just what a real Nato air campaign would involve, the source said. For his part, Gen Mladic embarked on a lengthy complaint about how badly the Bosnian Serbs had been treated, their right to statehood and so forth.
Gen Janvier was bearing unusually strict demands. He wanted an immediate end to attacks on the four UN-declared "safe areas" of Sarajevo, Tuzla, Bihac and Gorazde; the withdrawal of heavy weapons 20km from the capital; the re-opening without argument of the city's airport; and absolute freedom of movement for peace-keepers and aid workers through Serb-held territory.
In effect, he asked Gen Mladic to lift the siege. And, in a phrase that should have alerted the Serbs to the international mood, he warned that: "Bosnian Serb compliance with the terms of this agreement is not dependent on action, inaction or agreement by any other party." In the past, the UN argued that the secessionist Serbs could not be expected to pull back weapons unless the Bosnian government did too.
Gen Mladic exploded. The UN was trying to cast off the shackles with which his army has bound its every movement, and he was having none of it. His reply, in a letter seen by the Independent, agreed "in principle" to the removal of heavy weapons by "all parties", so long as "withdrawal will not confer advantages upon any party, nor alter the balance of forces".
As to the UN's movements in and out of Sarajevo, the peace-keepers were free to use one road "following existing and normal procedures". "Normal procedures" all too often meant the UN requesting permission and the Serbs denying it.
Gen Mladic had accepted Gen Janvier's main demands - but in time-honoured Bosnian Serb fashion, he hedged his letter of acceptance with conditions. This has worked on more occasions than UN officials can bear to remember: the world has been brought to the brink, offered a tiny ray of hope, and caved in to what proved to be broken paper promises.
At first, it seemed Gen Mladic had the measure of his man: Gen Janvier, perhaps exhausted by the marathon meeting, recommended an end to the Nato bombing campaign. But he did not count upon the fury of Western leaders. During a long meeting in Brussels on Saturday night of Nato ambassadors, the US envoy, Richard Holbrooke, architect of the unfolding peace process, and Willy Claes, Secretary-General of Nato, urged a renewal of the air campaign. Mr Holbrooke found the response "insulting", diplomats said; Mr Claes announced it was "not sufficient". Less diplomatically, the US ambassador to Nato called it "garbage".
As a result, a stiff reply was sent by the UN yesterday to Gen Mladic which reiterated the demands of Friday, but "with a greater clarity which precludes any qualifications", the official said. "It's much more of a fiat." The Bosnian Serbs, according to UN officials, have been given until 10pm London time tonight to lift the siege or face the possibility of devastating new Nato air-raids.