President Trump announced Friday evening that U.S. and Nigerian military forces had killed Abu-Bilal al-Minuki, a leader of the Islamic State group, in a "meticulously planned and very complex mission." Mr. Trump described al-Minuki as the Islamic State's second-in-command globally and "the most active terrorist in the world." "He will no longer terrorize the people of Africa, or help plan operations to target Americans," Mr. Trump wrote on Truth Social. "With his removal, ISIS's global operation is greatly diminished." The Nigerian president's office also confirmed the operation, and said that "early assessments confirm the elimination" of al-Minuki. "Several of his...