As the US special envoy, Richard Holbrooke, conducting eleventh-hour diplomacy in Pristina and Belgrade, Nato's Secretary General, Javier Solana, said in Brussels that "Nato is ready to act", adding: "Time is running out."
Last night Mr Milosevic was reported to have softened his stand in seven hours of talks with Mr Holbrooke, indicating willingness to comply with six main demands, including withdrawing more troops from Kosovo, allowing aid to the refugees and opening up serious talks with the secessionists on the restoration of their self-rule.
But he was refusing to make a key concession demanded by the US: the deployment of an international monitoring force in Kosovo which would include some Nato troops.
Earlier the US special envoy, continuing his efforts to broker a face- saving deal, held a 90-minute meeting in Pristina with the main ethnic Albanian political leader, Ibrahim Rugova.
In spite of American pressure for a speedy Nato "activation order", which gives the green light to military action, officials conceded this is unlikely to happen until tomorrow at the earliest.
Diplomats in Brussels and London insist that none of the 16 Nato members will obstruct the use of force, and that the allies' resolve has hardened during the last week.
But there remain complications in Bonn, where the new government has not yet been formed, and Rome, where Romano Prodi's coalition fell unexpectedly on Friday. The outgoing German cabinet is due to meet tomorrow afternoon. Diplomats believe that Bonn may approve Nato's action plan but not provide forces, as that would involve further discussions in the Bundestag.
In Rome yesterday, the caretaker defence minister, Beniamino Andreatta, delivered a message warmly welcomed by Nato, saying: "When our political authorities give the order, our armed forces are ready to join the armed forces of other countries... in the alliance to mount the maximum pressure so that law is restored in Kosovo."
Italy, which has vital air bases on its soil, would need parliamentary approval to join in Nato action, and centrist parties and the opposition centre-right bloc led by Silvio Berlusconi are expected to give their support. But the Communist Refoundation party, which Mr Prodi had relied on for a parliamentary majority, backs strikes only with further UN authorisation.
Russia continued to oppose the use of force, with its prime minister, Yevgeny Primakov, warning that there would be a "correction" in his country's relations with Nato if a strike goes ahead.
Nato officials said "a large percentage" of the Serbian special police units in Kosovo appeared to be digging in for the winter.
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