Nigeria's president Muhammadu Buhari purges defence top brass to take on Boko Haram Nigerian President Muhammadu Buhari has appointed new Defence chiefs and filled the post of National Security Adviser. According to a Presidential Spokesman, the move is expected to boost the fight against Boko Haram militants who have killed hundreds of people in the past few weeks. Major-General Abayomi Gabriel Olonishakin, previously Head of Army training, was named Chief of Defence Staff. The new Chief of Army Staff,Major General T.Y. Buratai, comes from Borno state, one of the worst hit by Boko Haram attacks. BBC