As fighting continued in the ravaged Serbian province, the sense grew that after a year of war in which 2,000 people have died and 300,000 lost their homes, the moment of truth is at hand.
This was "a critical turning point", the Nato Secretary-General, Javier Solana, said yesterday. "The next few days will be decisive."
Speaking on the eve of today's meeting in London of foreign ministers of the six-member Contact Group, Mr Solana said he expected the conference, which comprises France, Germany, America, Italy, Britain and Russia, to issue a "political ultimatum" for a settlement, which would be followed by a specific military ultimatum from Nato.
Based on proposals worked out by the American envoy Christopher Hill, the plan due to be endorsed by the six ministers meeting at Lancaster House will summon Belgrade and the ethnic Albanians to talks, perhaps as early as next week, to thrash out a deal for broad autonomy, though not full independence, for Kosovo.
It will be backed by an explicit threat by the alliance to Mr Milosevic that it stands ready at short notice to carry out airstrikes to force him to accept its demands.
These include the pull-back of Yugoslav army and police units to their levels of 12 months ago, full co-operation with the international monitors in the province, and unfettered access for United Nations war crimes prosecutors to investigate this month's massacre of 45 ethnic Albanians at Racak.
A warning to this effect was conveyed last night to the Yugoslav President by the Norwegian ambassador, Nato's senior representative in Belgrade.
Meanwhile, the build-up of allied forces in the region continued as a Nato naval group took up position in the southern Adriatic, and hundreds of allied warplanes were on 48 hours' preparedness to strike at Yugoslav military targets.
Adding to the pressure on Belgrade, Kofi Annan, the UN Secretary-General and a man usually associated with peace, not war, told the Atlantic Council that the military threat was essential to "the combination of force and diplomacy that is the key to peace in the Balkans".
The world community should have "no illusions about the need to use force when all other means have failed", he warned.
But the outcome last night was hanging in the balance, with no certainty that either party would attend a conference, and continuing skirmishes on the ground - in one of which two ethnic Albanians were killed and two Serbian policemen wounded.
In Belgrade, a spokesman for Mr Milosevic rejected an internationally sponsored conference and ruled out talks with "terrorists".
Nor was there much sign of the Albanians settling their own feud, between the political leadership under Ibrahim Rugova, and the Kosovo Liberation Army, which is waging the guerrilla war against the Serbs, and which is committed to full independence.
The formula envisaged for the talks resembles the Dayton conference of 1995, which yielded a settlement for the former Yugoslav republic of Bosnia. The talks could be held either in Austria or France.
They would begin as "proximity talks", mediated by Mr Hill and his EU opposite number, Wolfgang Petritsch, before moving on to face-to-face negotiations.
The main elements of the Hill package would be a three- year interim agreement, granting Kosovo its own parliament, police force and judiciary, and wide economic autonomy.