OUALLAM, Niger—The front lines in the war between the West and militant Islamists have shifted to Africa, from Somalia on the continent’s eastern tip to the West African Sahel, a semidesert strip south of the Sahara.
In the Sahel, the U.S. and its allies are betting that Niger, the worst-off country in the world by a U.N. measure, offers the best hope of stopping the seemingly inexorable spread of al Qaeda and Islamic State.