The letter, addressed to the Serbian President, Slobodan Milosevic, was delivered by hand by US diplomats in Belgrade at the end of last week. Its contents were confirmed yesterday by a senior Western diplomat. Mr Bush wrote that in the event of 'any military action in the Kosovo caused by Serbian action, the United States will be prepared to employ military force against the Serbians in the Kosovo and in Serbia proper'.
Options for deterring further Serbian aggression were discussed by Mr Bush and John Major during the Prime Minister's visit to Washington ten days ago. Although the letter's contents were not the subject of consultation, Lawrence Eagleburger, the US Secretary of State, telephoned the Foreign Secretary, Douglas Hurd, to tell him of the US decision.
The US is gaining ground in its efforts to push through a UN Security Council resolution authorising the use of force to impose the no-fly zone over Bosnia. The council held inconclusive closed-door discussions in New York yesterday.
The French Foreign Minister, Roland Dumas, said he believed the UN would decide in the next few days whether to enforce a no- fly zone, which could involve bombing Serbian positions. Britain, far more reluctant than the US and France about enforcement, was believed to be facing the inevitability of intervention.
In an article in today's Daily Telegraph Mr Hurd refers to the 'bloody-minded cruelty of the Serbs in Bosnia' and adds: 'We have to find a way of enforcing the no-fly zone without endangering the humanitarian effort.'
He says he distrusts military action as a way to force a settlement but the Serbs have brought even those who hold that view 'to the point where we can imagine armed action against them to prevent a general Balkan war'.
The greatest obstacle, Washington sources said, is the attitude of Russia. One Western diplomat remarked: 'They are not against the resolution in principle. But they are coming up with 55,000 reasons why it should not happen now.'
The Yugoslav parliament yesterday named Radoje Kontic as interim federal prime minister, hours after ousting Milan Panic, who lost an election challenge last week to replace Mr Milosevic as president. The US State Department issued an unusual written statement condemning the elections in Serbia and Montenegro as unfair and underlining that sanctions against the Milosevic regime will remain while its policies remain unchanged.
SARAJEVO - Amid rumours of an imminent Muslim assault to break the Serbian siege of the Bosnian capital, Mik Magnusson, a spokesman for the UN Protection Forces, said there were 10,000 men in the mountains around the city, 6,000 well armed and 4,000 in support roles, Reuter reports. Serbian tanks, armoured cars and troops crossed the Drina river and rolled into the Bosnian border town of Bratunac, besieged by Muslim forces.