"I don't think Washington is anywhere near accepting that," said one senior Nato source. "Blair has taken the lead but I don't think Germany is there. Don't forget, this could lead to unknown repercussions from Russia, and it could cause governments to fall in Italy, Greece and the Czech Republic."
Downing Street dismissed reports of a split as "nonsense" yesterday. But privately British government sources admitted that London was pressing Washington for an urgent decision on ground troops.
They also admitted there was frustration in Downing Street that the focus of debate in Washington has moved from sending in ground troops to a negotiated settlement, reflecting Mr Clinton's desire to avoid military casualties because of doubts among the public and in Congress.
One Whitehall insider said: "There is no threat to the Bill and Tony relationship, but we want to get a move on: we have to face up to the decision." The Foreign Secretary, Robin Cook, travels to Washington tomorrow to ease the deepening strains.
Mr Blair, due to visit Albania and Bulgaria today , insisted it was "not true" he was becoming increasingly frustrated by America's attitude to the war.
However, a clear difference of emphasis is suggested by reports that the US is stalling over the use of its "tank-busting" Apache helicopters, stationed in Albania but not yet deployed in combat missions. Last week Nato military sources made clear that pilot training is complete and the aircraft, equipped with "Hellfire" anti-armour missiles, are "ready to go".
General Wesley Clark, Nato's Supreme Allied Commander in Europe, is thought to be pressing hard for the use of the 22 Apaches against heavy armour dug in throughout Kosovo.
But The New York Times reported that the go-ahead has not been given because of fears in the Pentagon that the Apaches will be vulnerable to surface-to-air missiles. The newspaper quoted a Pentagon official as saying: "In an age when the American people believe we're in a zero-defects war, there's real apprehension we're going to bring soldiers back in body bags."
Asked about the timing of a decision on ground troops, Mr Blair told a Sunday newspaper: "We are well aware of the harshness of the Balkan winter and the impact that has. It is why Nato has been updating planning for all contingencies."
In the US the argument for ground troops is still being presented by the prominent Senator and presidential hopeful, John McCain. But the situation in Kosovo is no longer at the forefront of public attention, and neither a rousing speech by President Clinton to remind Americans of the reasons for the conflict, nor the visit to Macedonian refugee camps by the first lady, Hillary Clinton, stirred any passions.
Some in Downing Street are concerned that a decision may go by default if the White House does not address the issue, although Whitehall played down the idea of a May 31 deadline. One government source said: "There is no end-of-May cut-off. But the later you go the more dangerous and logistically difficult it becomes. It is a gradual process."
Nato is updating its contingency planning, with an option to enter Kosovo in a "semi- permissive" environment. Officials believe Britain needs support from the three key Nato powers - the US, France and Germany - before putting the question of ground troops before the decision-making North Atlantic Council.
Even then, the hawks would face an uphill battle. One official argued: "The only political support is for the campaign we have now."
In a joint editorial in yesterday's Washington Post, Mr Cook and the US Secretary of State, Madeleine Albright, said the "brutality" of President Slobodan Milosevic had stiffened their resolve to continue the Nato campaign.Reuse content