Nigeria World Buhari re-appoint Boss Mustapha and Abba Kyari Joseph AnthonyJuly 5, 20190119 views Muhammadu Buhari and Boss Mustapha President Muhammadu Buhari has approved the re-appointment of Mr Boss Mustapha as Secretary to the Government of the Federation (SGF), and Malam Abba Kyari as Chief of Staff (COS) to the President. Both appointments take effect from May 29, 2019.