Analysis on Monday by peace-keepers of the bloodstained crater proved "beyond all reasonable doubt" that the mortar bomb was fired by Bosnian Serb gunners south of Sarajevo. All options, including air-raids by Nato, or artillery barrages from the Anglo-French Rapid Reaction Force on Mount Igman, west of Sarajevo, were under consideration.
A small table bearing a few simple wreaths stood over the starburst pattern etched into the street by the 120mm mortar bomb. "None of them were my relatives, but they were all my fellow citizens, regardless of their names or religions," said one woman who brought roses to the site. "I am sick of the world, I am sick of Europe."
In Paris, where Richard Holbrooke, the diplomat pushing a new American peace initiative, met colleagues from the five-nation Contact Group on Bosnia, an international chorus demanded retribution.
But as night fell and Nato stayed silent, the Bosnian government, which threatened to boycott Mr Holbrooke's mission, and the people of Sarajevo, could be forgiven their scepticism and their anger.
"I think there will be no reaction - that is what the Serbs think, too," said Haris Silajdzic, the Bosnian Prime Minister. "They think there is a big green light burning for them so they can go on killing innocent people under the disguise of the peace process."
Still, Radovan Karadzic and the Bosnian Serb leadership in Pale were clearly nervous. Analysts believe their "parliament's" mild response to the US initiative on Monday was prompted in part by a desire to avert UN punishment.
A statement issued yesterday morning after an all-night session "welcomed" Mr Holbrooke's proposals, which amount to Bosnia's partition, and described a readiness to agree a "lasting and just peace".
It agreed to join a delegation led by rump Yugoslavia, but said nothing about surrendering territory. If forceful UN action might diminish the Serbs' willingness to talk, a lack of it may prove the final straw for the people of Sarajevo.
The US plan, still a work in progress, requires the Bosnian government to swallow some bitter pills. "As I see it, the new initiative makes two fairly major concessions to the Serbs, one constitutional and one with regard to the land question," said Michael Williams, of the International Institute for Strategic Studies.
The Sarajevo government is unhappy with the plans. "The Americans must be fearful now that if they don't do anything the Bosnian government will say: 'Forget it'," Mr Williams said. President Alija Izetbegovic yesterday demanded a response from Nato or the Rapid Reaction Force. Otherwise, he said: "Bosnian public opinion demands that we pull out of talks."
Should the UN decide to act, it has two choices. It can use air power for the "substantial and decisive response" promised at the London conference in July, or fire the French and British guns which are deployed on Mount Igman.
The former would, if the London conference was to be believed, involve wide-ranging air strikes against radar stations, ammunition dumps, command bunkers, even bridges - a kind of mini-Gulf war.
The latter - which is the option apparently favoured by Washington - would target Bosnian Serb guns around Sarajevo, whose locations have been well documented by teams attached to the Rapid Reaction Force. But it might also degenerate into massive fire-fights with Serb forces.
Despite the scepticism in Sarajevo, where dazed residents wandered past the scene of the crime yesterday in silence, or buried the victims in the city's crowded improvised graveyard, the hardest choice of all for the UN would be to do nothing.
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