United States

the US military's primary missions are to deter potential enemies, provide for the defense of the US, its Territories, Commonwealths and possessions, and any areas occupied by the US, and to protect US national interests; its responsibilities are worldwide and include providing humanitarian assistance, participating in international military exercises and operations, conducting military diplomacy, and fulfilling the US's alliance and treaty commitments; the US has been a leading member of NATO since the Alliance's formation in 1949 the US military has a global presence; the separate services operate jointly under 11 regional or functionally based joint service "combatant" commands: Africa Command; Central Command, Cyber Command, European Command, Indo-Pacific Command, Northern Command, Southern Command, Space Command, Special Operations Command, Strategic Command, and Transportation Command Congress officially created the US military in September 1789; the US Army was established in June 1775 as the Continental Army; after the declaration of independence in July 1776, the Continental Army and the militia in the service of Congress became known collectively as the Army of the United States; when Congress ordered the Continental Army to disband in 1784, it retained a small number of personnel that would form the nucleus of the 1st American Regiment for national service formed later that year; both the US Navy and the US Marines were also established in 1775, but the Navy fell into disuse after the Revolutionary War, and was reestablished by Congress in 1794; the first US military unit devoted exclusively to aviation began operations in 1913 as part of the US Army; the Army Air Corps (AAC) was the US military service dedicated to aerial warfare between 1926 and 1941; the AAC became the US Army Air Forces in 1941 and remained as a combat arm of the Army until the establishment of the US Air Force in 1947 (2025)

the US has approximately 200,000 military personnel deployed overseas on a permanent or a long-term rotational (typically 3-9 months) basis (2025)

United States Armed Forces (aka US Military): US Army (USA), US Navy (USN; includes US Marine Corps or USMC), US Air Force (USAF), US Space Force (USSF); US Coast Guard (USCG); National Guard (Army National Guard and Air National Guard) (2025)

note 1: the US Coast Guard is administered in peacetime by the Department of Homeland Security, but in wartime reports to the Navy

note 2: the Army National Guard and the Air National Guard are reserve components of their services and operate in part under state authority; the US military also maintains reserve forces for each branch

note 3: US law enforcement personnel include those of federal agencies, such as the Department of Homeland Security and Department of Justice, the 50 states, special jurisdictions, local sheriff’s offices, and municipal, county, regional, and tribal police departments

note 4: some US states have "state defense forces" (SDFs), which are military units that operate under the sole authority of state governments; SDFs are authorized by state and federal law and are under the command of the governor of each state; most are organized as ground units, but air and naval units also exist

17 years of age (under 18 with parental consent) for voluntary service for men and women; maximum enlistment age varies by service; 8-year initial service obligation, including 2-5 years active duty depending on the particular military service (2025)

note 1: the US military has been all-volunteer since 1973, but an act of Congress can reinstate the draft in case of a national emergency; males aged 18-25 must register with Selective Service

note 2: all military occupations and positions open to women; women comprised 17.7% of the total US regular military personnel as of 2023

note 3: non-citizens living permanently and legally in the US may join as enlisted personnel; they must have permission to work in the US, a high school diploma, and speak, read, and write English fluently; under the Compact of Free Association, citizens of the Federated States of Micronesia, the Republic of Palau, and the Republic of the Marshall Islands may volunteer

the US military's inventory is comprised almost entirely of domestically produced weapons systems (some assembled with foreign components) along with a smaller mix of imported equipment from a variety of countries such as Germany and the UK; the US defense industry is capable of designing, developing, maintaining, and producing the full spectrum of weapons systems; the US is the world's leading arms exporter (2025)

approximately 1.28 million active duty Armed Forces (450,000 Army; 334,000 Navy; 317,000 Air Force; 10,000 Space Force; 168,000 Marine Corps); 42,000 Coast Guard) (2025)