The global mission of the U.S. military may become increasingly challenged in the coming years by Chinese and Russian activities in Africa, according to the chief of U.S. Africa Command. Gen. Thomas Waldhauser said Tuesday he is monitoring foreign weapons sales and infrastructure investments in places like Djibouti, where China last year built its first overseas naval base near a military hub controlled by the United States. Waldhauser testified this morning before the House Armed Services Committee . He said...