Friday, August 11, 2006 Posted: 1931 GMT (0331 HKT)
U.S. intelligence officials said the plotters hoped to stage a dry run by Friday, The Associated Press reported. The actual attack would have followed days later, the officials told AP.
A senior congressional source said it is believed the plotters planned to mix a British sports drink with a gel-like substance to make an explosive that they would possibly trigger with an MP3 player or cell phone.
The sports drink could be combined with a peroxide-based paste to form a potent "explosive cocktail," if properly done, said a U.S. counterterrorism official.
"There are strong reasons to believe the materials in a beverage like that could have been part of the formula," the official said.
British and Pakistani authorities joined forces to block the plot to bomb the airliners, officials said.
British police acted urgently overnight, arresting 24 people in what U.S. government officials said privately could have been the biggest terrorist attack since September 11, 2001.
Among those arrested were a Muslim charity worker and a Heathrow Airport employee with an all-area access pass, according to Britain's Channel 4.
Five suspects in the plot are still at large, ABC News reported on its Web site, citing U.S. sources.
Information gathered after recent arrests in Pakistan convinced British investigators they had to act urgently to stop the plot, sources told CNN.
Pakistani authorities also made arrests in coordination with Britain, said a spokesman for the Pakistani Foreign Ministry. He did not say how many arrests were made.
U.S. Homeland Security Secretary Michael Chertoff said the plans were "suggestive of an al Qaeda plot," and President Bush said the arrests are a "stark reminder" that the U.S. is "at war with Islamic fascists."
Bush thanked British Prime Minister Tony Blair for "busting this plot."
Authorities immediately banned all passengers headed to or departing from U.S. airports from carrying any liquid in their carry-ons. The massive lines that resulted at security checkpoints made chaos of air travel worldwide as flights were delayed or canceled.
The effects of the plot rippled across the globe Thursday.
Chertoff said the plotters were "getting close to the execution phase."
"There were very concrete steps under way to execute all elements of the plan," he said.
The plot was "intended to be mass murder on an unimaginable scale," London's Metropolitan Police Deputy Commissioner Paul Stephenson said.
Chertoff said the plan was reminiscent of a plot by September 11 coordinator Khalid Shaikh Mohammed, who in 1995 had envisioned detonating bombs on 11 airlines possibly traveling over the Pacific Ocean.
The plot was "as sophisticated as any we have seen in recent years as far as terrorism is concerned," Chertoff said.
CNN terror analyst Peter Bergen said two factors pointed to the influence of al Qaeda. He said al Qaeda was "obsessed" with commercial aviation and that the timing of the plot was "very interesting."
"It's not clear when this was going to be implemented ... but we are coming up on the fifth anniversary of 9/11. They do want to make a big statement," he said on CNN's "American Morning."
The U.S. threat level has been raised to the highest level of "severe," or red, for commercial flights originating in the United Kingdom bound for the United States, according to the Department of Homeland Security. (Full story (http://edition.cnn.com/2006/US/08/10/us.terror.threat.text.ap/index.html))
In addition, the threat level has been raised to "high," or orange for all commercial flights operating in or coming to the United States, the DHS said.
The nation's overall terror threat level has not been altered.
Thursday was the first time the DHS has raised the threat level for a specific group of flights.
"Due to the nature of the threat revealed by this investigation, we are prohibiting any liquids, including beverages, hair gels, and lotions from being carried on the airplane," a DHS statement said.
Increased security means airline passengers around the country should show up at least two hours early for all flights, an official with the Transportation Security Administration told CNN.
British and U.S. security agencies quickly moved to impose strict limits on carry-on items in the wake of Thursday's arrests, causing extended delays at airport security checkpoints.
The British Airports Authority said no hand luggage would be allowed onto planes leaving British airports until further notice.
British Airways canceled all short haul flights in or out of Heathrow Airport for Thursday, and delays were stacking flights up at airports across Europe.