In the United States, that difference of opinion appears to have extended to the government and the military.

Crucially, US President Bill Clinton - without whose approval such an operation would be impossible - is still extremely wary of a public opinion backlash in the event of American casualties in Kosovo.

The BBC's Paul Reynolds: "There is also the question of the timetable for moving troops"

However, media reports suggest that the US military sees the commitment of troops as essential to achieve alliance's aims.

Of the other Nato countries, the UK is signalling that it is most strongly in favour of driving the Serb military out with ground forces, while Germany and Italy seem to be building for an early end to the conflict through diplomacy.

The most notable American critic of Nato policy has been former US General Colin Powell, who masterminded the United Nations campaign in the Gulf Conflict.

The principle of using overwhelming force to achieve defined political objectives - the so-called Powell doctrine - is not being pursued in Kosovo, he said on Sunday.

He told an American television network: "And so the Powell doctrine would suggest that once you pick a political objective, you then apply the appropriate means to achieve that objective.

"Go all out, yes, and war involves casualties."

That view has allegedly been reinforced by the US Joint Chiefs of Staff in a letter to the US Defence Secretary William Cohen - sent several weeks ago, but only recently leaked from the Pentagon.

General Powell: "Appropriate means"

Published in Newsweek magazine, the letter states that bombing alone will not achieve Nato's objectives and that troops will eventually be needed.

Newsweek's National Security Correspondent John Barry told the BBC: "It does come at a significant time because the generals realise that we are running out of time in Kosovo.

"Winter begins in Kosovo in the middle of October and the military are telling the administration that they need to have troops on the ground by the beginning of August in Kosovo if they are to sort out the refugee chaos before the snows come.

"And if they have to do that then they have to start planning for it by the beginning of June. So time pressure is really beginning to tell on President Clinton."

White House Correspondent for the New York Daily News, Tom De Frank, said US polls suggesting public approval for Nato action in Kosovo could change rapidly in the face of casualties.

The loss of two US aircrew in an Apache helicopter training accident was enough to delay deployment of the formidable anti-tank aircraft in Kosovo, he said.

"There is a growing sense of isolation in this country. I have always said that Americans like military expeditions as long as nobody gets killed.

"It's also a function of the fact that the president and all of his principle advisers worked very hard to avoid military service in their younger days.

KLA: Fighters say the Yugoslav army is demoralised

"I don't think they understand the military, I don't think they appreciate the military and I don't think they understand that the military option, while unpleasant, is sometimes the only credible option."

But UK Foreign Secretary Robin Cook has suggested that planning of a sort for the deployment of ground forces is already under way.

"We did, in Washington three weeks ago, set in hand the planning for all options in which we could take troops into Kosovo to take the refugees back," he said.

"We asked [Nato Secretary General] Javier Solana to do that. And what he is doing is planning to take advantage of the success of the campaign that we are currently carrying out.

Nato: Officially the bombs are working

He said that he had spoken to the head of the Kosovo Liberation Army, who confirmed that Yugoslav troops were "more demoralised than ever and are deserting in very significant numbers".

"We are making an impact in Kosovo. We must be ready to take advantage of that when the time comes," he said.

Nonetheless, former US Secretary of State, Lawrence Eagleburger, says that deployment of troops is likely to remain too politically unpalatable for US President Bill Clinton to commit to it.