In a forthright speech in London Wednesday, President Bush tackled his critics head-on, as tens of thousands of them gathered for a planned protest march through the streets of the British capital Thursday.
Mr. Bush defended the war in Iraq and called for more international support to spread democracy throughout the world.
But skeptics in continental Europe saw little in his comments to convince them that US policy in the Middle East stands much chance of success.
"The greatest danger of the age," the president warned, is "nuclear, chemical, and biological weapons in the hands of terrorists and the dictators who aid them. The evil is in plain sight. The danger only increases with denial."
That repetition of the rationale for toppling Saddam Hussein, however, will win few converts in Europe, where US troops' failure so far to find weapons of mass destruction in Iraq, and the lack of any evidence linking Hussein to Al Qaeda, has undermined US credibility in many citizens' view.
Beyond the confident rhetoric, however, Washington's newfound desire to hand power over to Iraqis by next June falls more clearly in line with arguments that European leaders have been voicing for months - that the US-led occupation of Iraq should be as short as possible.
The US president's visit to Britain, initially planned more than a year ago and later presumably imagined as a celebration of success in Iraq, has come at an awkward time for British Prime Minister Tony Blair, who is having difficulty persuading his country that the war was justified.
But Bush showed no signs of doubt about his decision to use military might against Baghdad. "In some cases, the measured use of force is all that protects us from a chaotic world ruled by force," the president told an invited audience of academics in the keynote speech of his three- day state visit to London.
In the face of mounting violence against US troops in Iraq, however, where the death toll has topped 400, Washington appears anxious to reassure an increasingly dubious American public by scaling down its presence in Iraq as soon as possible.
Reversing their earlier insistence that a constitution should be written and elections held before the US-led Coalition Provisional Authority could hand political power over to Iraqis, US officials are now looking to next June as their deadline for establishing a provisional government.
US Secretary of State Colin Powell met European Union foreign ministers in Brussels on Tuesday, seeking their backing for the new US timetable, and explaining how he sees the United Nations role in the planned transition.
The shift in US thinking, which appears to reflect the sort of arguments that European political leaders had been urging on Washington for several months, has won a mixed reception in Europe.
British officials have welcomed it, and German Foreign Minister Joschka Fischer said Monday it was a "very important step forward."
The French government, however, continues to insist that Washington has not gone far enough. The June horizon "is too late," French Foreign Minister Dominique de Villepin said in an interview with the daily La Croix on Monday. "We should move faster," he added.
Mr. de Villepin suggested that the 25-member Iraqi Governing Council could be expanded to form an assembly that would elect a provisional government within the next six weeks. That government would gradually take over the reins of executive government from US officials, he proposed, while American troops would remain in Iraq to maintain order.
The only way to combat the "terrorist networks, nationalist resistance, and Islamist groups" which de Villepin blamed for mounting attacks on US soldiers, is "to give Iraqis back their sovereignty," he argued.
European leaders have also strongly - but so far unsuccessfully - urged the US to give the United Nations a central role in guiding Iraq's political transition to democracy, which de Villepin said would give that process "legitimacy."
Mr. Powell told European ministers that he did envision a UN role, but there are no signs yet that Washington is prepared to cede CPA chief Paul Bremer's control of Iraqi politics to any outside institution.
Without such a move, it is hard to imagine any more Western European countries joining the Spanish, Italian, British, Dutch, and Danish troops currently helping America keep the peace in Iraq, despite Powell's pleas for more international assistance on Tuesday.
Already there are suspicions among many European observers that the US administration is asking for foreign troops to replace American soldiers in Iraq so as to boost President Bush's chances of reelection next November.
"It seems to me that Bush is [facing] huge political problems and expects the rest of the world to get him out of them," British Labour Party member of Parliament Jeremy Corbyn told BBC television on Wednesday.