Defense Secretary Ash Carter has given his top commanders the green light to allow more troops to carry weapons at U.S. bases, with a focus on recruiting stations, Reserve centers and other softer military targets. Carter’s actions came two weeks after a Kuwaiti-born gunman killed four Marines and a sailor before police slayed him at the Navy reserve center in Chattanooga, Tenn. “The tragic shooting on July 16 in Chattanooga, Tennessee, illustrates the continuing threat to DOD personnel in the U.S. homeland posed by homegrown violent extremists,” Carter wrote in a memo released Thursday by the Pentagon. In the memo,...