The United States Armed Forces are the military forces of the United States.As stated on the official U.S. Navy website , "armed forces" is capitalized when preceded by "United States" or "U.S." United States federal law establishes six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard, each assigned specific roles and operational domains. and . With the exception of the Coast Guard, which operates under the Department of Homeland Security (DHS) in peacetime, the services are organized under the Department of Defense (DoD).
Established during the American Revolutionary War, the Army and the Navy, and later the other services, have played a decisive role in the country's history. They contributed to early national consolidation through conflicts such as the Barbary Wars and the War of 1812, shaped the country's territorial evolution, and were involved in global conflicts including World War I, World War II, the Cold War, and the war on terror.World Book Encyclopedia, 2025 ed., s.v. "War" The National Security Act of 1947 reorganized the military establishment by creating the DoD, the Air Force, and the National Security Council; in 1949, an amendment to the act merged the cabinet-level departments of the Army, Navy, and Air Force into the DoD.Kinnard, Douglas. "The Secretary of Defense in Retrospect." The Secretary of Defense. Lexington: University of Kentucky, 1980. 192–93. Print. formalizing a unified defense structure under civilian control. The Space Force was established in 2019 as the newest branch.
The president of the U.S. serves as commander-in-chief and exercises authority over the armed forces through the DoD and, for the Coast Guard in peacetime, DHS. Since 1973, the United States has maintained an all-volunteer force, although the Selective Service System remains authorized to conscript most male citizens and residents aged 18 and 25 to register. All six services are also among the eight uniformed services of the United States. The armed forces consist of active-duty personnel, Reserve components, and the National Guard.
The U.S. Armed Forces are widely considered the world's most powerful and most advanced military. The military expenditure of the U.S. was US$957 billion in 2025, the highest in the world, accounting for 33% of the world's military expenditures. The personnel size of the six armed forces together ranks them among the world's largest state armed forces. The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enable widespread deployment of the force globally, including around 800 military bases around the world.
History
The history of the U.S. Armed Forces dates back to 14 June 1775, with the creation of the Continental Army, even before the Declaration of Independence marked the establishment of the United States. The Continental Navy, established on 13 October 1775, and Continental Marines, established on 10 November 1775, were created in close succession by the Second Continental Congress in order to defend the new nation against the British Empire in the American Revolutionary War.
These forces demobilized in 1784 after the Treaty of Paris ended the Revolutionary War. The Congress of the Confederation created the current United States Army on 3 June 1784. The United States Congress created the current United States Navy on 27 March 1794 and the current United States Marine Corps on 11 July 1798. All three services trace their origins to their respective Continental predecessors.
The 1787 adoption of the Constitution gave Congress the power to "raise and support armies," to "provide and maintain a navy", and to "make rules for the government and regulation of the land and naval forces", as well as the power to declare war. The president of the United States is the United States Armed Forces' commander-in-chief.
The United States Coast Guard traces its origin to the formation of the Revenue Cutter Service on 4 August 1790, which merged with the United States Life-Saving Service on 28 January 1915 to establish the Coast Guard.
The United States Air Force was established as an independent service on 18 September 1947; it traces its origin to the formation of the Aeronautical Division, U.S. Signal Corps, which was formed 1 August 1907 and was part of the Army Air Forces before being recognized as an independent service in the National Security Act of 1947.
The United States Public Health Service Commissioned Corps was formerly considered to be a branch of the United States Armed Forces from 29 July 1945 until 3 July 1952, and is now one of the eight uniformed services of the United States. Should it be called into active duty again, it would constitute a seventh branch of the Armed Forces.
The United States Space Force was established as an independent service on 20 December 2019. It is the sixth branch of the U.S. military and the first new branch in 72 years. The origin of the Space Force can be traced back to the Air Force Space Command, which was formed 1 September 1982 and was a major command of the United States Air Force.
The U.S. Congressional Research Office annually publishes a List of Notable Deployments of U.S. Military Forces Overseas since 1798.
Structure Presidential command over the U.S. Armed Forces is established in Article II in the Constitution whereby the president is named as the "Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States."
The United States Armed Forces are split between two cabinet departments, with the Department of Defense serving as the primary cabinet department for military affairs and the Department of Homeland Security responsible for administering the United States Coast Guard.
The military chain of command flows from the President of the United States to the secretary of defense (for services under the Defense Department) or secretary of homeland security (for services under the Department of Homeland Security), ensuring civilian control of the military.
Within the Department of Defense, the military departments (Department of the Army, Department of the Navy, and Department of the Air Force) are civilian led entities that oversee the coequal military service branches organized within each department. The military departments and services are responsible for organizing, training, and equipping forces, with the actual chain of command flowing through the unified combatant commands.
Joint Chiefs of Staff
The Joint Chiefs of Staff, although outside the operational chain of command, is the senior-most military body of the Department of Defense. It is led by the Chairman of the Joint Chiefs of Staff, who is the principal advisor to the president and secretary of defense on military matters. Their deputy is the Vice Chairman of the Joint Chiefs of Staff. Both the Chairman and Vice Chairman are barred from exercising military command over the Joint Chiefs of Staff or any of the armed forces with the exception of the Joint Staff.
Other members include the chief of staff of the Army, commandant of the Marine Corps, chief of naval operations, chief of staff of the Air Force, chief of space operations, and the chief of the National Guard Bureau.
The commandant of the Coast Guard is not an official member of the Joint Chiefs, but sometimes attends meetings as one of the military service chiefs.
The senior enlisted advisor to the chairman is the most senior non-commissioned officer (NCO) in the United States Armed Forces and is a unique enlisted rank which only one individual may hold it. Is the primary enlisted advisor to the chairman, and serves at the pleasure of the secretary of defense.
The president of the United States, the secretary of defense, the secretary of homeland security and chairman of the Joint Chiefs of Staff are members of the United States National Security Council, which advises the president on national security, military, and foreign policy matters.
The national security advisor, the homeland security advisor, and the deputy national security advisor may also be members of the United States Armed Forces.
The National Security Council Deputies Committee also includes the deputy secretary of defense, deputy secretary of homeland security, and vice chairman of the Joint Chiefs of Staff.
Military leadership, including the secretary of defense, the secretary of Homeland Security, and chairman of the Joint Chiefs of Staff also sit on the National Space Council.
Unified combatant commands
Unified combatant commands are joint military commands consisting of forces from multiple military departments, with their chain of command flowing from the president, to the secretary of defense, to the commanders of the combatant commands.
Each service organizes, trains, and equips forces that are then presented to the unified combatant commands through service component commands. Special Operations Command and Cyber Command also present theater special operations commands or joint force headquarters – cyber to other combatant commanders.
Army components are typically dual-hatted as the joint force land component, Navy components are typically dual-hatted as the joint force maritime component, and Air Force components are typically dual-hatted as the joint force air component, with the theater special operations command dual-hatted as the joint force special operations component, and Space Force component typically dual-hatted as the joint force space component.
NameMissionHeadquartersSubunified commandsU.S. Africa Command (USAFRICOM)Conducts U.S. military operations in Africa.Kelley Barracks, GermanyU.S. Central Command (USCENTCOM)Conducts U.S. military operations in the Middle East and Central Asia.MacDill Air Force Base, FloridaU.S. Cyber Command (USCYBERCOM)Conduct U.S. military cyber operations.Fort Meade, Maryland Cyber National Mission ForceU.S. European Command (USEUCOM)Conducts U.S. military operations in Europe.Patch Barracks, GermanyU.S. Northern Command (USNORTHCOM)Conducts U.S. military operations in North America and homeland defense operations.Peterson Space Force Base, Colorado Alaskan CommandU.S. Pacific Command (USPACOM)Conducts U.S. military operations in the Indo-Pacific.Camp H. M. Smith, HawaiiU.S. Southern Command (USSOUTHCOM)Conducts U.S. military operations in Central America, South America, and the Caribbean.Doral, FloridaU.S. Space Command (USSPACECOM)Conducts U.S. military operations in outer space.Peterson Space Force Base, ColoradoU.S. Special Operations Command (USSOCOM)Develops and employs special operations forces. MacDill Air Force Base, FloridaU.S. Strategic Command (USSTRATCOM)Conduct strategic deterrence, nuclear operations, nuclear command, control, and communications, joint electromagnetic spectrum operations, and global strike.Offutt Air Force Base, NebraskaU.S. Transportation Command (USTRANSCOM)Conduct globally integrated mobility operations.Scott Air Force Base, Illinois
Combat support agencies
Combat support agencies are Department of Defense agencies with combat support missions that service operating forces planning or conducting military operations. This includes support during conflict or in the conduct of other military activities related to countering threats to U.S. national security. This mission is focused on providing support to echelons at the CCMD level and below and may not encompass the full scope of the CSA's mission.