US reactionThe White House yesterday framed the terrorist plot, apparently thwarted in the UK, as a direct attack on the US. American officials tightened airport security nationwide in response to the news from London.
With officials describing the plot as the greatest terrorist threat to the US since September 11th, George Bush called the arrests a "stark reminder" that the country was "at war with Islamic fascists who will use any means to destroy those of us who love freedom, to hurt our nation".
Speaking in Wisconsin, the president said: "It is a mistake to believe there is no threat to the United States of America."
US Muslim groups criticised Mr Bush's description of the foiled plot as a "war with Islamic fascists", saying the term could inflame anti-Muslim tensions. "We believe this is an ill-advised term and we believe that it is counterproductive to associate Islam or Muslims with fascism," said Nihad Awad, executive director of the Council on American-Islamic Relations advocacy group.
Delays grew at airports after homeland security officials banned all liquids and gels from aircraft cabins, except for baby formula and medicines.
Federal security officials were focusing on John F Kennedy airport in New York, Dulles airport outside Washington, and Los Angeles International airport as the probable destinations of the aircraft involved, they told state-level officials privately.
A spokesman described officers at the US Northern Command in Colorado as "a little bit more vigilant" than normal.
Additional armed air marshals had left the US for London yesterday, where they were to join US-bound flights, mingling unidentified with passengers, the homeland security department said. One of the carriers reportedly targeted in the plot, American Airlines, cancelled several flights to London, blaming delays at Heathrow.
US officials emphasised a suspected link with al-Qaeda. The homeland security secretary, Michael Chertoff, called the disrupted plans "suggestive of an al-Qaeda plot", while Robert Mueller, the FBI director, said the scheme "had the earmarks of an al-Qaeda plot". A senior counter-terrorism official told the Associated Press that up to 50 people might have been connected to the conspiracy.
Alberto Gonzales, the attorney general, suggested there might be prosecutions in the US, although there had been no arrests or evidence of plotting on American soil.
By Wednesday, Mr Chertoff said, the potential attackers "had accumulated and assembled the capabilities they needed, and were in the final stages of planning for execution".
Citing the British legal system as a reason for withholding further information, officials painted a picture of close collaboration between British and American investigators that had been stepped up in the last two weeks. Mr Chertoff said that was when Washington had received the first definitive clues that the plot would target American planes specifically.
But there was still uncertainty, he said, "about whether the British have scooped up everybody".