As a child (sometimes in the 80’s or early 90’s) I read a book about a brilliant and charismatic Cold War era African leader who uses military cunning to successfully invade two of his neighboring countries (I believe Togo and Benin) .
The plot revolves around the leader setting the two countries against one another by having a mercenary frame one country for planting a bomb in the other. The leader than promises each country his support in a future war, but ends up invading and taking over both countries.
The book features an American or British white citizen visiting the country, befriending the African leader and falling in love with with a black tall singer. He joins the final battle in the book.
I also recall a minor scene where a pedophile communist spy was able to discover the plot by getting a government official drank, but he is killed prior to being able to share the info.
Another character is a British white secretary which works for the African leader and becomes his mistress.
I did extensive online research but could not find the book.