The U.S. Army chain of command begins at the top with the sitting president, who is considered the commander-in-chief of all the nation's armed forces. The president is then followed by the Joint Chiefs of Staff, particularly the chairman, and the Army Chief of Staff. Other important bureaucratic influences on army affairs are the Secretary of Defense, the Secretary of the Army and the Sergeant Major of the Army.
After these highest authorities, the army chain of command breaks down further by area of operation. For instance, after the army chief of staff, authority falls to the top commander in any given theater, such as Europe, Africa or the Pacific. Additionally, the army possesses several non-regionally oriented commands that may achieve semi-autonomous status, such as the Special Operations, Training and Doctrine, Deployment and Distribution, and Army Space and Missile Defense commands.
After identifying either the theater of operations or independent entity, the chain of command progresses through units by decreasing size. The highest-ranking figure is the corps commander, followed by the division, brigade and battalion heads. At the most immediate combat and training levels, command falls first to the company or troop commander, and then finally to the platoon leader and section, squad or team leader.