"We also know that al Qaeda in the Arabian Peninsula ... continues to plan attacks against our homeland, our citizens, and our friends and allies," he said during a press briefing on the incident.
One suspicious package, found at the UK's East Midlands Airport, contained a "manipulated" toner cartridge and had white powder on it as well as wires and a circuit board, a law enforcement source said. A similar package set to be shipped on a FedEx cargo plane was discovered in Dubai, the law enforcement source and Dubai officials said.
"Initial examination of those packages has determined they do apparently contain explosive material," Obama said.
The source close to the investigation said the type of material found in the devices was PETN, a highly explosive organic compound belonging to the same chemical family as nitroglycerin. Just six grams of PETN is enough to blow a hole in the fuselage of an aircraft.
PETN was allegedly one of the components of the bomb concealed by Umar Farouk AbdulMutallab, the Nigerian man accused of trying to set off an explosion aboard Northwest Airlines Flight 253 as it approached Detroit, Michigan, on December 25. AbdulMutallab is alleged to have been carrying 80 grams of PETN in that botched attack -- also believed to be the workings of al Qaeda in the Arabian Peninsula.
By comparison, the source said the two devices found Friday contained multiple times more PETN. The source also said it appears the devices were designed to be detonated by a cell phone with the help of a smaller amount of a second unidentified explosive substance.
The cell-phone theory was seconded by a wireless engineer for a major U.S.-based manufacturer, who analyzed a photo of one of the devices at CNN's request.
