Hours after a crucial television address, President Bill Clinton will today begin consultations with Congressional leaders to convince them of his case that national credibility, the stability of Europe and simple moral duty all dictate that the US must send 20,000 troops to help Nato keep the peace in a post-war Bosnia.
Last night's speech was one of the most important of his Presidency, as Mr Clinton assumed the role in which, by common consent, he is least comfortable - that of commander-in-chief. Barring renewed fighting in the next few days or weeks, American soldiers undoubtedly will go to the Balkans. But without Congressional and public backing, he would be left perilously exposed if the mission went wrong.
The message, in the words of Warren Christopher, the Secretary of State, yesterday, was that Bosnia had become an "acid test" of US leadership, that without American leadership there would have been no peace deal, and "without our troops, an agreement that serves our interests will not be carried out".
Although polls still show a majority against putting the lives of US servicemen at risk, the mood seems to be shifting cautiously the President's way.
In London, the Secretary of State for Defence, Michael Portillo, yesterday confirmed that Britain would provide about 13,000 troops as part of the Implementation Force (IFOR). The enabling force, including signals and movements staff to prepare for the main body, will start moving in the next few days, before the final signature of the ceasefire agreement.
In Sarajevo UN relief workers expressed concern that tens of thousands of Bosnian Serbs would leave Serb-held districts of Sarajevo rather than live in a Muslim-Croat federation, as envisaged under the Dayton peace settlement. "There has been so much propaganda, so much hostility and hatred that I don't think they will be taking chances. They will simply leave," said Kris Janowski, spokesman for the UN High Commissioner for Refugees in Sarajevo.
Their departure would undermine hopes of restoring Sarajevo to its pre- war tradition of tolerant co-existence among Muslims, Croats and Serbs and would consolidate Bosnia's de facto partition into separate Muslim- Croat and Serb zones.
Thousands of Sarajevo Serbs staged demonstrations last weekend against the Dayton agreement, and their leader, Radovan Karadzic, predicted the city would become "the Beirut of Europe".
Mr Karadzic seems determined to undermine the Sarajevo part of the settlement because the handover of Serb city districts to the Muslim-Croat federation would threaten his base at Pale, the rebel headquarters outside the capital. It would simultaneously enhance the importance of the largest Bosnian Serb city, Banja Luka, where Serb rivals to Mr Karadzic have accepted the deal.
The EU's mediator for former Yugoslavia, Carl Bildt, rejected Mr Karadzic's complaints.