The Islamic terrorists arrested in London in August apparently were planning to detonate their bombs aboard airplanes above American cities.

A group of alleged terrorists arrested in London in August planned to blow up airliners over U.S. cities to maximize casualties, rather than over the Atlantic Ocean as many intelligence officials originally thought, according to recent remarks by a senior FBI official.

The comments by Mark Mershon, head of the FBI’s New York field office, indicate that U.S. and British intelligence officials now think that the airliner plot was aimed at maximizing the potential loss of life and economic impact.

“The plan was bring them down over U.S. cities, not over the ocean,” Mershon said Oct. 24 at the Infosecurity 2006 conference in New York, according to Government Security News, which first reported the remarks this week. ...

Mershon told cybersecurity conference attendees that representatives of MI5, the British intelligence service, briefed the FBI on the liquid explosives case in recent weeks. “It would make your hair stand up to be in the room to hear that presentation,” Mershon said, according to GSN.

Bruce Hoffman, a terrorism expert and Georgetown University professor, said the case indicates that Islamic extremists remain focused on attacking U.S. cities.

“They were clearly desirous of exceeding 9/11,” Hoffman said. “The loss of life on the air and ground would be significant.”