An improvised explosive device built by sewing explosives inside the underwear fabrics. It is designed to evade airport metal detectors as it doesn't contain any metal components. The bomb is intended to be worn by a suicide passenger bomber who sets it off once on board by manually activating a sophisticated detonation system.

The CIA thwarted an al-Qaeda plot in Yemen to destroy a U.S.-bound airliner using an improved version of the underwear bomb around the one-year anniversary of the killing of Osama bin Laden. This incident has helped to reinforce the importance of full-body scanners, which have the ability to detect non-metallic explosives.