JOHN IRISH and MICHEL ROSE FRENCH military forces have killed the leader of a West African affiliate of Islamic State by a drone strike in a "decisive blow" against the group and vowed to continue hunting down jihadist leaders to restore stability in the Sahel. Adnan Abu Walid al-Sahrawi was the head of the Islamic State in the Greater Sahara (ISGS), a jihadist group that broke away from other militants in Mali in 2015 when it pledged allegiance to Islamic State. Since then, ISGS militants have spread into neighbouring Burkina Faso and Niger, carried out hundreds of deadly attacks on…