CAIRO – Al-Qaida's chief bomb maker, Ibrahim al-Asiri, who was behind the 2009 Christmas Day plot to down an airliner over Detroit and other foiled aviation-related terror attacks, was killed in a U.S. drone strike, Yemeni officials and a tribal leader said Friday. The killing of al-Asiri deals a heavy blow to the group's capabilities in striking western targets and piles pressure on the group that already lost some of its top cadres over the past years in similar drone strikes. A Yemeni security official said that al-Asiri is dead; a tribal leader and an al-Qaida-linked source also said that he was killed in a U.S. drone strike in the eastern Yemeni governorate of Marib. The tribal leader said that al-Asiri was struck, along with two or four of his associates, as he stood beside his car. He added that al-Asiri's wife, who hails from the well-known al-Awaleq tribe in the southern governorate of Shabwa, was briefly held months ago by the UAE-backed forces and later released. Al-Qaida itself has remained silent about its top bomb maker.

ADEN, Yemen – Al-Qaida in the Arabian Peninsula, based in Yemen, is considered the most dangerous branch of the terror network after a series of failed attacks on U.S. soil. AQAP has been enmeshed in conflicts in impoverished Yemen for nearly 20 years -- at times working with the government and at times facing crackdown, all the while building ties among tribes in the mountainous countryside to establish refuges and allies. The first anti-American attack in Yemen linked to al-Qaida took place in 1992 when a group called the Islamic Jihad Movement attacked a hotel in the southern city of Aden housing U.S. troops heading to Somalia, killing a Yemeni and an Australian. The group was made up of jihadis who had returned from Afghanistan, where they fought the Soviets alongside Osama bin Laden. The group fell apart after defections spurred by its cozy relationship with ruling authorities as then-President Ali Abdullah Saleh used AQAP fighters to liquidate his top foes, the socialists.