The Scotsman reports that Tony Blair has told President Bush that the U.K. cannot participate in any military action against Iran:

Tony Blair has told George Bush that Britain cannot offer military support to any strike on Iran, regardless of whether the move wins the backing of the international community, government sources claimed yesterday.

Amid increasing tension over Tehran's attempts to develop a military nuclear capacity, the Prime Minister has laid bare the limits of his support for President Bush, who is believed to be considering an assault on Iran, Foreign Office sources revealed.

Blair's "favorite think tank" has produced a report arguing that the Iranian crisis can be defused through diplomacy and engagement:

The Foreign Policy Centre (FPC), often referred to as Blair's "favourite think-tank", will appeal for a greater effort to find a diplomatic solution in a report to be published later this week. FPC director Stephen Twigg, formerly a Labour minister, explained: "It is essential UK policy on Iran is well informed... We want to engage with the various reformist elements in Iran, both inside and outside the structures of power.

"There is potential for political dialogue, economic ties and cultural contacts to act as catalysts for the strengthening of civil society in Iran."

Somehow I don't find any of that very reassuring. But if President Bush does decide to pull the military trigger--which I consider highly unlikely--it looks like he will have to proceed without America's closest ally.