N' DJAMENA( Reuters)-Chad has decided to recall half of its 1, 200 troops battling Islamist militants in the tri-border area of Mali, Burkina Faso and Niger, a spokesperson for the Chadian authorities said on Saturday. Chad deployed the soldiers in February to support a France-backed regional fight with insurgents linked to al Qaeda and Islamic State who have destabilised swathes of territory in West Africa's Sahel region in recent years. The decision to withdraw 600 of these soldiers was taken