The National Security Council: An Organizational Assessment
"The National Security Council (NSC) was established by statute in 1947 to
create an inter-departmental body to offer confidential advice to the President on all aspects of national security policy. Currently, statutory members of the Council are the President, Vice President, the Secretary of State, and the Secretary of Defense; but, at the President’s request, other senior officials participate in NSC deliberations. The Chairman of the Joint Chiefs of Staff and the Director of National Intelligence are statutory advisers. In 2007, the Secretary of Energy was added to the NSC membership.

The President clearly holds final decision-making authority in the executive
branch. Over the years, however, the NSC staff has emerged as a major factor in the
formulation (and at times in the implementation) of national security policy.
Similarly, the head of the NSC staff, the National Security Adviser, has played
important, and occasionally highly public, roles in policymaking. This report traces
the evolution of the NSC from its creation to the present."