A US drone strike in northwestern Syria killed a Yemeni leader of a local jihadist group affiliated to Al-Qaeda, the US military and a Syrian war monitor said.The strike, carried out on Monday just before midnight (2100 GMT) on the eastern edge of the city of Idlib, took out a man described as a leader of the Hurras al-Deen group. "Abu Hamzah al Yemeni was travelling alone on a motorcycle at the time of the strike," US Central Command said in a statement, adding that an "initial review indicates no civilian casualties".