10 U.S.C. § 163: Role of Chairman of Joint Chiefs of Staff

direct that communications between the President or the Secretary of Defense and the commanders of the unified and specified combatant commands be transmitted through the Chairman of the Joint Chiefs of Staff; and assign duties to the Chairman to assist the President and the Secretary of Defense in performing their command function. The Secretary of Defense may assign to the Chairman of the Joint Chiefs of Staff responsibility for overseeing the activities of the combatant commands. Such assignment by the Secretary to the Chairman does not confer any command authority on the Chairman and does not alter the responsibility of the commanders of the combatant commands prescribed in section 164(b)(2) of this title . confer with and obtain information from the commanders of the combatant commands with respect to the requirements of their commands; evaluate and integrate such information; advise and make recommendations to the Secretary of Defense with respect to the requirements of the combatant commands, individually and collectively; and communicate, as appropriate, the requirements of the combatant commands to other elements of the Department of Defense.