The Chief of Staff of the Army (abbreviated as CSA) is a statutory office (10 U.S.C. § 3033) held by a four-star general in the United States Army, and is the most senior uniformed officer assigned to serve in the Department of the Army, and as such is the principal military advisor and a deputy to the Secretary of the Army; and is, in a separate capacity, a member of the Joint Chiefs of Staff (10 U.S.C. § 151), and thereby a military advisor to the National Security Council, the Secretary of Defense, and the President. The Chief of Staff is typically the highest-ranking officer on active-duty in the U.S. Army unless the Chairman and/or the Vice Chairman of the Joint Chiefs of Staff are Army officers.