A U.S. drone strike in Somalia has killed a key leader of the al-Shabab militant group who was involved in two attacks in Mogadishu more than a year ago, killing Americans, several U.S. officials said Friday. Hassan Ali Dhoore and two others were killed in the strike Thursday about 20 miles south of Jilib in southern Somalia not far from the Kenya border, the officials said. They said Dhoore helped facilitate a deadly Christmas Day 2014 attack at the airport and a March 2015 attack at the Maka al-Mukarramah Hotel, both in Mogadishu. U.S. citizens were among those killed in the two attacks, the officials said. One senior official also said that Dhoore was believed to be involved in plotting more attacks that would have targeted U.S. citizens.