Organizational structure of the United States Department of Defense

The President of the United States is, according to the Constitution, the Commander-in-Chief of the U.S. Armed Forces and Chief Executive of the Federal Government.

The President and the Secretary of Defense exercise authority and control of the Armed Forces through two distinct branches of the chain of command.

The Act permits the President to direct that communications pass through the Chairman of the Joint Chiefs of Staff from the Secretary of Defense and the Unified Combatant Commanders.

Further, the Act gives the Secretary of Defense wide latitude to assign the Chairman oversight responsibilities for the Unified Combatant Commanders' activities.

Article II Section 2 of the Constitution designates the President as "Commander in Chief" of the Army, Navy and state militias.

Most notably, during the Korean War, General Douglas MacArthur ignored civilian instructions regarding advancing troops toward the Yalu River, which triggered an introduction of massive forces from China.

Also, on April 5, 1950, Representative Joseph William Martin Jr., the Minority Leader of the United States House of Representatives, released copies of a letter from MacArthur critical of President Harry S. Truman's limited-war strategy to the press and read it aloud on the floor of the house.

For example, DoD Directive 1344.10 prohibits active-duty members of the military from running for office or making political appearances in uniform.

As another example, at a September 14, 2007, rally for Republican Presidential candidate John McCain in New Hampshire, seven on-duty uniformed Army personnel addressed the gathering.

On 1 March 2003 the Secretary of Defense lost Executive Agent responsibilities for the National Communications System, which was moved to the Department of Homeland Security.

Department of Defense Field Activities are established as DoD Components by law, the President, or the Secretary of Defense to provide for the performance, on a DoD-wide basis, of a supply or service activity that is common to more than one Military Department when it is determined to be more effective, economical, or efficient to do so, pursuant to sections 101, 191(a), and 192 of Title 10 of the United States Code.

This proposed significant changes to the areas of responsibility for other adjacent geographical commands as shown in the accompanying graphic.The Office of the Inspector General is an independent and objective unit within the Department of Defense that conducts and supervises audits and investigations relating to the programs and operations of the Department of Defense, pursuant to the responsibilities specified in title 5, U.S.C.

The NGB is the focal point at the strategic level for National Guard matters that are not under the authority, direction, and control of the Secretaries of the Army or Air Force, including joint, interagency, and intergovernmental matters where the NGB acts through other DoD officials as specified in DoDD 5105.77.