Robert Ludlum's The Bourne Betrayal by Eric Van Lustbader

Jason Bourne has only one friend in the CIA: Martin Lindros. And he has disappeared in Africa while tracking shipments of yellowcake uranium. Bourne takes on the mission to rescue his friend. With Lindros safely home, Bourne agrees to help find the terrorists who are buying nuclear material. But he soon suffers from confusing flashbacks. Is someone brainwashing him in order to throw him off the trail? Worse still, is the man he saved really Martin Lindros? Now Bourne is on his own -- gathering evidence, while trying to stay one step ahead of the terrorists who are determined to destroy the USA.

(Jason Bourne #5)