By Barnaby Mason BBC diplomatic correspondent

A confrontation between the United States and its key European allies has been brought out into the open by Washington's decision to veto the extension of UN authorisation for peacekeeping in Bosnia.

For the moment, the Americans are saying their troops will stay in Bosnia as part of S-For, this force will not be affected.

All the same, Nato ambassadors were called into special session in Brussels to consider the implications.

The current president of the European Union, Denmark, put out a statement deeply regretting the American move: a dramatic step, it said, that threatened UN peace operations in general.

That interpretation was backed by the US ambassador to the UN, John Negraponte:.

He said that unless the problem was satisfactorily resolved, it would come up again and again - meaning whenever a UN mandate has to be renewed.

Stark disagreement

Some observers now wonder whether the logical end of the campaign will be a United States decision to stop paying its share of the UN peacekeeping budget, just over a quarter of the total.

The US veto has exacerbated existing differences

There have been many disagreements between the United States and its allies in western Europe.

But this time the Americans are in open conflict in the security council not only with France but also with Britain, their closest partner.

The British Foreign Secretary, Jack Straw, said Britain was involved in intensive discussion with the Bush administration to try to allay its fears about the International Criminal Court which had provoked the use of the veto.

Mr Straw denied that Britain's relations with the United States were under threat.

But on this issue the disagreement is stark.

European governments were a little slow to appreciate the lengths to which the administration was prepared to push its opposition to the International Criminal Court

The creation of the new court is dear to Tony Blair's heart; it fits into the particular moral orientation that he has given to British foreign policy - if not always consistently carried out.

It is becoming harder for his government to argue that such disputes are merely an inevitable part of what remains a close relationship.

Only last week Mr Blair, in common with almost all of Europe, declined to back Mr Bush's demand for Yasser Arafat to be removed as Palestinian leader.

Europeans puzzled

The crisis over the court takes its place in a growing history of political friction between Washington and the European Union.

Critics of Mr Bush see it as another example of unilateralism, similar to his administration's abandoning of the biological weapons convention and the Kyoto Treaty on global warming.

Europeans are less inclined to be sympathetic given Washington's determination to deny to the terrorist suspects it holds the normal protection of the American judicial system

European governments were a little slow to appreciate the lengths to which the administration was prepared to push its opposition to the International Criminal Court, reinforced by its unrelenting focus on the war against terrorism.

The Europeans do not believe the stated American objections to the Court are reasonable, given the safeguards against frivolous or politically motivated prosecutions.

And they are less inclined to be sympathetic given Washington's determination to deny to the terrorist suspects it holds the normal protection of the American judicial system.

The transatlantic gulf is getting wider.

To its European and other critics, United States opposition to the Court seems to be based on a fundamental unwillingness to limit American sovereignty in any way.