Nigeria's Boko Haram battle stalls as population starves

Nigeria's military campaign against Boko Haram Islamists is increasingly bogged down as it confronts suicide attacks, looting and indiscriminate slaughter while the UN warns the affected region faces the "largest crisis in Africa". In northern Borno state, the epicentre of the insurgency that has spread to three neighbouring countries -- Chad, Cameroon and Niger -- Nigeria's army has unleashed a barrage of air and land assaults. The counter-insurgency has clawed back some territory, but Boko Haram has responded by stepping up guerrilla tactics, ambushing troops when it can and terrorising civilians when it cannot.