Despite international promises to punish attacks on UN "safe areas" in Bosnia, the attack on Sarajevo brought widespread expressions of horror mixed with determination to continue the peace process.
The death by mortar fire of least 37 Sarajevans "will only make us redouble our effort," said Richard Holbrooke, US Assistant Secretary of State.
Baroness Chalker, Minister for Overseas Development, said in London that the attack illustrated the urgent need for a political solution, though the shadow foreign secretary, Robin Cook, said the authority of the international community in Bosnia would be undermined if UN forces did not hit back.
Carl Bildt, the European Union envoy, called it "the strongest argument we can find for going forward with the peace process."
The UN could not apportion certain blame; but officials noted that the fire came from an area mostly controlled by the Bosnian Serbs. The Bosnian government demanded the suspension of the peace process and air strikes by Nato.
The alliance has not ruled out any options, but Western politicians keen for a resolution of the Bosnian war may find it hard to sanction air raids against the Bosnian Serbs just as Mr Holbrooke embarks on another diplomatic round. Although the decision to call in the jets rests with the French UN commander, General Bernard Janvier, he is unlikely to act without authorisation from Paris.
Britain described the attack as senseless - but the fatal mortar was fired with a purpose, probably that of complicating Mr Holbrooke's peace mission.
Sarajevo's response to the US proposals - which amount to the partition of Bosnia - has been less than enthusiastic, but the government long ago accepted an international peace deal.
It is the Bosnian Serb leadership in Pale that fears the Holbrooke deal, analysts in Belgrade say, particularly the demand that Belgrade and its delegates speak for the rebel Serbs in Bosnia.
Radovan Karadzic, the Bosnian Serb leader, is already out of favour with Serbia and risks losing power, money and influence - everything - if President Slobodan Milosevic is induced to lead the negotiations.
Time is running out for Mr Karadzic; on Sunday Mr Holbrooke warned Pale that it had only weeks to accept a peace deal or risk serious Nato involvement. So far, the rebel Serbs have proved extremely canny in estimating the Western stomach for a fight. Even as world leaders at the London conference in July promised a forceful defence of the UN-declared safe areas in Bosnia, Mr Karadzic's troops were storming the enclave of Zepa.
Ordinary Bosnians long ago surrendered dreams of international intervention; officials struggle against outside political pressure to throw in the towel and accept what they see as an unjust peace. But neither side believes that Nato and the UN have the political will to act forcefully against the Bosnian Serbs. It remains to be seen whether Mr Karadzic and his colleagues in Pale, who have played the world and won, have made their first fatal error.
SARAJEVO'S HISTORY OF TERROR
1 March 1992: Bosnia chooses independence from Yugoslavia in majority vote by Muslims and Croats. Vote boycotted by Serbs, who declare their own "republic".
6 April: EU and US recognise Bosnia. Pro-independence Bosnians storm rebel Serb headquarters in Sarajevo's Holiday Inn hotel. Yugoslav army and Bosnian Serb irregulars seal off city. Siege begins.
27 May: Twenty killed and 70 wounded in mortar attack on bread queue, first of a series of atrocities against civilians. Attack blamed on Serbs. Serbs claim Bosnian troops fired at own people in an effort to blame the Serbs and provoke Nato intervention.
4 Sept: Italian plane flying aid to Sarajevo is shot down and four crewmen killed. UN believes culprits may have been Bosnian Croats at odds with the mostly Muslim government.
May 1993: Young couple, one a Muslim and the other 1993 a Serb, shot dead while trying to flee Sarajevo. Bodies cannot be retrieved for days because of gunfire in the area.
30 May: Sixteen Sarajevans die in intense Serb artillery bombardment of densely populated city neighbourhoods.
1 June: Two mortar bombs land in car park where young men are playing soccer, killing 15 people and wounding 100.
12 July: Twelve civilians die in mortar attack on residents queuing at a water well in the suburb of Dobrinja, because power cuts have knocked out pumps supplying water to homes.
22 July: Sarajevo weathers one of worst bombardments in 24-hour period since the war began as 3,777 shells pummel the city. About 10 civilians are killed and scores wounded.
9 Nov: Mortar bomb lands just outside Sarajevo school, killing nine children and a teacher.
22 Jan 1994: Mortar bomb falls among children playing in snow, killing six and wounding 35 in attack blamed by UN on Serbs.
5 Feb: Mortar bomb hits crowded market in centre of city, killing 68 people and wounding around 200 in worst single atrocity of war in Bosnia. Serbs deny responsibility for attack. Source never definitively fixed, since shell was fired from front-line zone.
29 July: Serbs target vehicles on sole government supply road into Sarajevo. British soldier killed in Serb attack on UN convoy.
28 Aug 1995: Thirty-seven people were killed and dozens wounded when mortar bomb lands in crowded street near Sarajevo's central market.