Protecting John Doe

Security aboard flights into Glasgow Airport was beefed up two weeks ago with protection by U.S. air marshals who are now on board every inbound and outgoing European flight, according to a Homeland Security official.

Air marshals also began guarding flights into Prague at the same time, and in May stepped up coverage to guard all flights into and out of Germany, where terrorists are reportedly in the advanced planning stages of an attack. Air marshals are also guarding some flights into South Asia airports.

An official who asked to remain anonymous said suspicious events aboard flights have been reported and are being investigated but declined to reveal any details of the events.

"There is so much going on out there. We do know these guys are definitely in an operational phase right now," the official said.