Defense Secretary Ashton B. Carter has fired his top military aide for allegations of “misconduct,†a highly unusual move prior to a formal investigation into possible misbehavior by the Army general. In a statement, Carter said that he had removed Lt. Gen. Ron Lewis from his position as senior military assistant. As his top military aide, Lewis was a right-hand advisor to Carter, providing him analysis on military issues, joining him at high-level meetings, and traveling with him on overseas missions. Carter said the Pentagon’s Inspector General would investigate the allegations against Lewis and, if necessary, the Army would take...