There was a mood of grim resignation at Westminster that the air strikes which had been recalled in mid-flight in November would now go ahead after the damning report of Richard Butler, head of the UN weapons inspectors in Iraq.
"Nobody who reads that report can seriously doubt the conclusion that Unscom [the special weapons commission] is unable to carry out its role properly," Mr Blair said.
"This is not obstruction for the sake of it. It is a plan of deceit to prevent these weapons of mass destruction being located and destroyed.
"Saddam Hussein, if allowed to develop these weapons of mass destruction, poses a threat not just to his neighbourhood but to the whole world."
The Conservative leader, William Hague, pledged the support of the Opposition. Most Labour MPs appeared ready to back the action, although left-wingers called for a mass vigil against the bombing outside Downing Street.
The Labour MP George Galloway accused President Bill Clinton of making "a last ditch attempt to avoid humiliating impeachment" by ordering the bombing. Comparing this to Wag the Dog, the US film in which a president starts a war to protect himself, Mr Galloway said: "Britain is playing the role of the tail to a very ill-bred dog. Clinton - already condemned as a liar, cheat and deceiver - has no compunction about saving his own skin with the blood of innocent men, women and children in Iraq."
President Clinton and the Prime Minister agreed the action in a 10-minute telephone call between London and Washington at midday yesterday. It followed a 15-minute call from the President to brief Mr Blair on Tuesday night on the Butler report as Mr Clinton flew back to Washington from the Middle East.
The Prime Minister told the Commons on 16 November that there would be "no warnings, no wrangling, no negotiation and no last-minute letters. The next time co-operation is withdrawn, he will be hit." Downing Street confirmed last night that this time there would be no official warning to Iraq.
The determination within the Government to end the cat-and-mouse game with President Saddam was matched by a widespread feeling at Westminster that unless that threat was carried out this time, the credibility of the British-US alliance would be wrecked.