... The more lasting damage will derive from the shoddy, humiliating way Mr. Trump treated the secretary and his generals on such a core military issue as deployments in Syria. Jim Mattis is not some neoconservative bent on staying in Syria for years. He is less hawkish on Syria and Iran than national security adviser John Bolton or Secretary of State Mike Pompeo. Yet in deciding to withdraw all U.S. troops from Syria, Mr. Trump acted on his own impulses with little more than cursory consultation with his military advisers. Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff,...