British Prime Minister Tony Blair claimed that there was "complete unanimity, not just across the European Union but I would say across the civilised world, that we need both in our own countries and internationally to decide what are the measures we require in order to hit this international terrorism at every single level, its finances, its method of operation, the dangers that it poses".
Blair will appeal to African leaders to join a worldwide fight against terrorism when he holds a pre-arranged summit at his Chequers country residence.
Later, he will seek to ensure that Germany rallies strongly behind America when he meets Chancellor Gerhard Schroeder in Berlin.
But the mood in many European capitals has been more restrained, indicating that the alliance in support of Washington is broad rather than deep.
While President George W. Bush described the aftermath of the assaults on his country as "the first war of the 21st century" his European counterparts have tended not to see things the same way.
Lionel Jospin, the French Prime Minister, insisted that "we are not at war against Islam or the Arab-Muslim world", a sentiment endorsed by Louis Michel, the Belgian Foreign Minister.
Under pressure from its coalition parties, Belgium entered reservations before signing up to the article five decision in Nato.
Even Nato Secretary-General Lord Robertson sidestepped the question of whether Nato was at war, saying it was not relevant.
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