Clashes between jihadist groups are increasing as they seek to strengthen their territorial control, Jama'a Nusrat ul-Islam wa al-Muslimin' (JNIM), the Sahel's largest jihadist umbrella alliance, is under pressure from an aggressive fightback by Islamic State in the Greater Sahara (ISGS), determined to reinforce its hold over much of Ménaka region in north-east Mali.