For all the stern words from Washington about possible military action against Iran if it fails to rein in its nuclear ambitions, the US would almost certainly have to mount such a campaign without the backing of Britain, its staunchest ally in Iraq, according to experts.
On Monday, US President George W. Bush said he could not rule out using force if Washington was unable to persuade Tehran to abandon a nuclear energy program it charges is cover for developing atomic weapons, while secretary of state-designate Condoleezza Rice called for world action on the issue.
A report in the New Yorker magazine this week said US commandos had been operating inside Iran since the middle of last year to search out potential targets for attack.
Overall, the Bush administration "recognizes that a military attack against Iran's military facilities is not a very attractive option," said Gary Samore, a specialist on Iran at the International Institute of Strategic Studies think tank in London.
"There are many drawbacks, both practical and political," Samore told reporters, adding that the Pentagon was undoubtedly "examining the options for a pre-emptive military strike" against Iran's nuclear and missile facilities.
A game of diplomatic bluff was underway, with Washington hopeful that the threat of military action might pressure Britain and other European Union nations to negotiate forcefully with a worried Tehran so as to head off war, he explained.
"In a way, the American threat to bomb Iran is also indirect pressure on Europe to do its very best, to achieve a diplomatic solution," he said, adding that Bush would find it extremely difficult to find backing in Europe for military action.
"Even if British officials recognize that the threat of a military attack may help their diplomatic efforts with Iran, I have not been able to find a British official, much less French or German, who thinks that a military attack actually makes sense," he said.
"My guess is that the British government would at best be silent, at worst be opposed."
Much would depend "on who the British hold responsible for the failure of diplomacy," he added.
"If the British feel that the US has been unreasonable and unsupportive of British diplomatic efforts, then obviously London will be less inclined to support the US."
British Prime Minister Tony Blair, whose popularity has been badly dented by his decision to back the US-led conflict in Iraq, would be extremely wary of getting his nation involved in another conflict, added Katarina Dalacoura from the International Relations department at the London School of Economics.
It "would not make sense for [the British government] to do that, especially given all the flak they have received over Iraq," she said.