Reserve component of the Armed Forces of the United States

The reserve components of the United States Armed Forces are military organizations whose members generally perform a minimum of 39 days of military duty per year and who augment the active duty (or full-time) military when necessary. The reserve components are also referred to collectively as the Guard and Reserves.

According to 10 U.S.C. § 10102, the purpose of each reserve component is to provide trained units and qualified persons available for active duty in the armed forces, in time of war or national emergency, and at such other times as the national security may require, to fill the needs of the armed forces whenever, during and after the period needed to procure and train additional units and qualified persons to achieve the planned mobilization, more units and persons are needed than are in the regular components.

The seven reserve components of the U.S. military are:

The civilian auxiliaries of the U.S. military are not considered reserve components of the respective Services, but could assist the military in peacetime or wartime; the exception is the Coast Guard where upon determination by the Commandant of the Coast Guard, members of the Coast Guard Auxiliary become part of the Temporary Reserve (per the Coast Guard Authorization Act of 1996):

During times of war, the Merchant Marine may transport military supplies and personnel, but Merchant Mariners are not military personnel. However, in the 1980s, some Merchant Mariners, who had sailed during the Second World War, were granted veteran status.

Additionally, under the U.S. Constitution, each sovereign State (or Commonwealth), may have additional organized militia, such as the various State naval militias and State guards. These militia forces are not considered reserve components because they are not federally recognized, even though they may perform a military function. State naval and defense forces may be organized as each State requires, usually report to the State Adjutant General (the Federally-recognized commander of all National Guard forces in each State), and are trained and equipped to perform specialized roles such as search and rescue, maritime patrols, augmenting state police or National Guard military police in a law enforcement role, or emergency management response. These forces may be armed or equipped, and have powers of arrest, as each State requires, and as State forces are not subject to the limitations of the Posse Comitatus laws governing Federal military forces' engaged in law enforcement duties.

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