The good news is that Congress can stop him.
POTUS’s executive order giving Steve Bannon a seat on the National Security Council’s Principals Committee is an assault on common sense and tradition—that much is obvious. It also appears to be a violation of federal law.
According to Title 50 of the U.S. Code, Section 3021, which established the National Security Council, it “shall be composed of” the president; the vice president; the secretaries of state, defense, and energy; and “the secretaries and undersecretaries of other executive departments and of the military departments, when appointed by the President by and with the advice and consent of the Senate, to serve at his pleasure.”
As the president’s chief political strategist, Bannon is not a secretary or undersecretary of any department. Nor, as a member of the White House staff, has he been confirmed by the Senate. So he is not eligible to serve on the NSC, and if that’s the case, he is doubly ineligible to sit on its Principals Committee—the assembly of Cabinet secretaries and department heads (sometimes including the president) that discusses and makes decisions on high-level U.S. foreign and military policy.
POTUS’s executive order of Jan. 28, titled “Presidential Memorandum: Organization of the National Security Council and the Homeland Security Council,” affirms that the Principals Committee “shall continue to serve as the Cabinet-level senior interagency forum for considering policy issues that affect the national security interests of the United States.” The memo then goes on to state that the committee’s “regular attendees” shall include the secretaries of state, treasury, defense, and homeland security; the attorney general; and the national security adviser, who formally calls such meetings. (The director of national intelligence and the chairman of the Joint Chiefs of Staff are also invited to attend “when issues pertaining to their responsibilities and expertise are to be discussed.”) All this is consistent with the committee’s composition under Presidents Barack Obama and George W. Bush.