Man on Flight to Detroit Claims Al Qaeda Ties; Obama Tightens Security DETROIT -- A passenger on a Detroit-bound Northwest Airlines flight tried to detonate an explosive device that was strapped to his leg and later told investigators that he was trying to blow up the plane and had affiliations with al Qaeda, according to a senior U.S. official. The man, who has not been publicly identified by officials, told investigators that he was given the device by Al Qaeda operatives in Yemen, where he was also given instructions on how to detonate it, the official said. The Associated Press...