LONDON: As a piece of geopolitical theater, the timing was hard to beat. Chad’s foreign minister announced the end of military cooperation with France just hours after his French counterpart left the country. That it took place on Nov. 28, as Chad celebrated its Republic Day—a key date in its move away from French colonial rule—only added to the symbolism. On the same day, Senegal also suggested French troops should leave. It was a seminal moment in post-colonial relations between France and the Sahel—the belt of nations south of the Sahara that stretches across Africa.