The most worrisome aspect was Mr. Trump's decision to insert Mr. Bannon as a regular member of his National Security Council, the prime security and foreign-policy body in the White House. Mr. Bannon's elevation to the NSC Principals Committee coincided with the demotion of both the chairman of the Joint Chiefs the Staff, the nation's ranking military leader, and the director of national intelligence, the top spymaster and security official; these regular designees of the Principals Committee under Mr. Obama will not routinely attend the committee's meetings.