British Authorities Foil Plot To Bomb U.K.-To-U.S. Flights

Homeland Security raises threat level on all commercial flights.

British authorities announced Thursday (August 10) that they had foiled a terrorist plan to blow up multiple airliners traveling between the United Kingdom and the United States, a plot "to create mass murder on an unimaginable scale."

Twenty-one people have been arrested in connection with the plot, which involved smuggling explosives onto as many as 10 airplanes in carry-on luggage. CBS News reports that the targeted flights were headed toward U.S. airports including New York's John F. Kennedy International Airport, Washington, D.C.'s Dulles International Airport and Miami International Airport.

In response to the arrests, all flights into London's Heathrow Airport were canceled, and airlines banned carry-on luggage on all departing planes.

Here in the U.S., the Department of Homeland Security raised the threat warning to its highest level for commercial flights coming from Britain, and has banned passengers from bringing beverages, hair gels and lotion into the aircraft cabin, explaining that the liquids had emerged as a risk stemming from the investigation in Britain. Homeland Security Secretary Michael Chertoff said that the terrorist plot revolved around "liquid explosive devices."

It marks the first time in the National Threat Advisory's four-year history that the government has raised of the threat level to red ("severe"). In a statement made early Thursday morning, Chertoff said the move was a "prudent" one.

"This plot appears to be well-planned and sophisticated ... it was international in scope. The operation is suggestive of an al Qaeda plot, but we cannot form a definitive conclusion," Chertoff said. "We believe that these arrests [in London] have significantly disrupted the threat, but we cannot be sure that the threat has been entirely eliminated or the plot completely thwarted."

Chertoff also announced that the threat level on all commercial flights, domestic and international, would be raised from yellow ("elevated") to orange ("high"), adding that travelers can expect additional security measures within airports and at screening checkpoints.

President Bush, en route to a fundraising event in Oneida, Wisconsin, spoke briefly to reporters on the tarmac of Austin Straubel International Airport in Green Bay, praising the joint efforts between U.S. and U.K. intelligence outfits and urging patience for travelers inconvenienced by increased security procedures.

"The cooperation on this venture between U.K. and U.S. officials was solid," Bush said. "This country is safer than it was prior to 9/11, and we've taken a lot of measures, but obviously we're not completely safe. ... It is a mistake to believe that there is no threat of harm to the United States of America. Travelers are going to be inconvenienced because of the steps we've taken. I ask them to be patient. ... We live in a dangerous world and we will do anything we can to keep them safe."

Meanwhile, British police continued their investigation, searching homes and businesses in cities including London and Birmingham. Paul Stephenson — London's deputy metropolitan police commissioner — would not identify the 21 people being held in connection with the plot, nor would he reveal their nationalities. But he did hint at the scope of the plan, calling it "extraordinarily serious."

"We are confident that we have stopped an attempt to create mass murder on an unimaginable scale," Stephenson told reporters. "We have been very successful in arresting those we were targeting, but this is a lengthy operation, and no doubt there will be further developments."

For continuing coverage of this developing story, head to CBSNews.com.

[This story was originally published at 8:52 a.m. ET on 08.10.06]