Each state in the United States has a senior military officer, as the state adjutant general, who is the de facto commander of a state's military forces, including the National Guard residing within the state, the state's naval militia, and any state defense forces. This officer is known as TAG, and is subordinated to the chief executive. They do not have authority over police forces, only military forces.

The National Guard is a state-based military force that becomes part of the U.S. military's reserve components of the U.S. Army and the U.S. Air Force when activated for federal missions. It is a military reserve force composed of National Guard military members or units of each state and the territories of Guam, the Virgin Islands, Puerto Rico, and the District of Columbia, for a total of 54 separate organizations. It is officially created under Congress's Article 1 Section 8 ability to "raise and support armies". All members of the National Guard are also members of the organized militia of the United States as defined by 10 U.S.C. § 246. National Guard units are under the dual control of state governments and the federal government.