Coming soon: the moment when Blair must choose between Europe and the US

The Bush administration brushed aside European calls for a postponement of an attack on Iraq yesterday, declaring that United Nations weapons inspections would not work.

The President told Iraqi commanders they would be tried as war criminals if they used weapons of mass destruction against invading US troops.

Such fierce talk makes life more uncomfortable for Britain and Tony Blair, bringing nearer the moment when that consummate rider of two horses may finally have to choose between the US and Europe.

Last night, as Jack Straw, the Foreign Secretary, arrived in Washington for talks with Colin Powell, the Secretary of State, British diplomats were saying, in effect, no problem. But even they could not ignore the insistence of France, Germany and others that the inspectors must be given the time to do their job and that any use of force against Saddam Hussein had to be backed by a second Security Council resolution.

General Powell had seemed the closest to a sympathiser among Mr Bush's top advisers. But even he signalled yesterday he had lost patience. "The question isn't how much longer do you need for inspections to work. Inspections will not work."

Hours later, Mr Bush stepped up the rhetoric. "We must not be fooled as in the past," he said in remarks aimed at friends abroad as much as at a cheering audience in St Louis. "He wants to play a game. But for the sake of peace we must not let him. The resolutions of the Security Council will be enforced."

He issued a separate warning to President Saddam and the "killers" in Baghdad. Should the US go to war, he said, there would be "serious consequences" for any Iraqi general or soldier who used weapons of mass destruction on US troops. "My advice is, don't follow that order ­ or when Iraq is liberated you will be tried and prosecuted as a war criminal."

But around the world, even in the US itself, opposition was growing to the hard line in Washington and London. At a meeting of Nato ambassadors, France and Germany blocked a decision on whether to authorise support measures in any US-led war against Iraq. "The arguments were flying," one diplomat said.

Germany's Chancellor, Gerhard Schröder, stated for the first time that Germany would not back an Iraq war resolution in the Security Council, where it takes over the rotating presidency next month. From Russia, a permanent member of the council that opposes military action, came a report that the US and Britain had already decided on mid-February to begin military action.

Although that date is at the earliest end of the likely spectrum, up to 150,000 American troops will be deployed by then, ready to attack. Ratcheting up the pressure, Donald Rumsfeld, the Defence Secretary, has ordered two more aircraft carrier battle groups to the Gulf, bringing to four the number based near Iraq.

Mr Bush's speech was part of an orchestrated campaign to meet the central domestic criticism of his Iraq policy: that for all the belligerence, he has not made the case for war.

If a crucial moment looms for Britain, Mr Bush has unfamiliar problems of his own. A Washington Post­ABC News poll yesterday showed the approval rating of a man who was until recently the most popular president in modern history continuing to decline, to below 60 per cent from more than 90 per cent after 11 September.

Worries about Iraq and the flagging US economy are starting to outweigh support for his conduct of the "war on terrorism". Mirroring opinion in Europe, seven out of 10 Americans believe the inspectors should be given several months more to complete their work.

Washington is fighting back with its own PR ahead of the UN inspectors' report to the Security Council on Monday. The White House has issued a report called Apparatus of Lies, laying bare Baghdad's "brutal record of deceit".

On Tuesday, Mr Bush will deliver his verdict in his State of the Union address. Three days later, Tony Blair goes to Camp David, where a final decision for war may be taken. That is, if it hasn't been taken already.