British police made the decision to move in and make arrests when they learned several of the men had booked flights to the U.S. in the next several days, for apparent trial runs.
It turns out British authorities have known of the airline plot for months, where it started and who helped organize and pay for it.
"We have been looking at meetings, movement, travel, spending and the aspirations of a large group of people," said Peter Clarke, head of Scotland Yard’s anti-terrorism branch.
Intelligence officials tell ABC News the plot’s trail leads to Pakistan’s largest city, Karachi, where money for the plot was wired to London.
Officials say two of those arrested in London came here in the last few months for explosives training with known al Qaeda commanders.
"It clearly is an al Qaeda-type operation with links to al Qaeda," Rep. Pete King (R-NY), Chairman of the House Homeland Security Committee, said.
There were several arrests also made in Pakistan today in connection with the case, but the suspected ringleader remains at large. Pakistani officials say this 29-year old al Qaeda commander, Matiur Rehman, was known to be planning a terror spectacular to mark the fifth anniversary of the 9/ll attacks. The London plot may well have been it.
According to Alexis Debat, a Senior Fellow at the Nixon Center and ABC News Consultant, who is in Pakistan, "Matiur Rehman is crucial because he is the interface between al Qaeda’s leadership and thousands, if not tens of thousands, of Pakistani militants."
The London plot is a carbon copy of another foiled al Qaeda effort, in 1995, to blow up 11 U.S. aircraft over the Pacific.
It was led by now imprisoned al Qaeda leader Ramzi Yousef. "Ramzi Yousef was going to bring on the plane, in liquids secreted in contact lens fluid and put this into, saturated material into a stuffed doll that he was going to put on the plane and explode with a Casio watch," explained Jack Cloonan, former FBI agent and ABC News consultant.
As British authorities continue to hunt for five other suspected terrorists, there is growing concern there could be a plan B. "They’re out there," said Rep. King. "If nothing else, they’re available for future operations. The more deadly threat is that there is a plan B that they would be able to implement."