The closing of almost two dozen U.S. embassies throughout North Africa and the Middle East appears to be in part based on a fear of a new generation of liquid explosives, according to two senior U.S. government officials.
Though liquid explosives have long been a threat, the new explosive takes the challenge of detection a step further. Terrorists would be able to dip clothing into the liquid that would turn into an explosive when dry.
"It's ingenious," one of the officials said. The other added the explosive is not detectable by current security measures.
The new technique is believed to have been developed by the Yemen-based al Qaeda affiliate AQAP, or al Qaeda in the Arabian Peninsula. The Arabian Peninsula is where Ibrahim al-Asiri, the notorious bomb maker suspected of being behind the Christmas Day underwear bomb, resides.
"As always, our security posture, which at all times includes a number of measures both seen and unseen, will continue to respond appropriately to protect the American people from an ever evolving threat picture," a TSA official said, though the organization did not comment specifically on the new explosive.