Usman Yusuf, a vocal Nigerian professor of Haematology-Oncology and Bone Marrow Transplantation, has warned President Bola Tinubu not to get entangled in a messy proxy geopolitical war between Nato and Russia in Niger following a recent dramatic coup led by General Abdourahmane Tchiani against the deposed president Mohamed Bazoum. Tchiani is Russian-backed, while Bazoum is…