Principal military adviser to the
President of the United States of America, the
Secretary of Defense, and the
National Security Council. Presides over the
Joint Chiefs of Staff. Though this
position is considered the
senior ranking
member of the
Armed Forces of the
United States, he
cannot command combatant forces. However, he may
transmit the commands of the President or Secretary of Defense to the the commanders of those forces.
Source: www.dtic.mil/jcs/