Umar Farouk Abdulmutallab is shown in this file booking photograph released by the U.S. Marshals Service December 28, 2009. The revelation that militants sought to attack an airliner with an improved "underwear bomb" in a plot foiled by U.S. and allied authorities shows their determination to build bombs that can pass through airport security, U.S. officials said on May 7, 2012. On Christmas Day in 2009, Nigerian-born militant Abdulmutallab who had spent time in Yemen, tried to detonate a bomb sewn into his underpants as his flight from the Netherlands to Detroit began its descent in U.S. airspace. The device burst into flames but its explosive charge did not detonate. Abdulmutallab was subdued by fellow passengers and was later jailed by U.S. authorities.