Guide to the United States Armed Forces

Header guide to armed forces


Less than 10% of the US population has served or currently serves in the US Armed Forces,1 following a downward trend since the end of World War II.2 As a result, fewer Americans are familiar with the basic details of the US Armed Forces. This guide is designed to provide a brief overview and basic facts about the Department of Defense (DOD) and America’s Armed Forces.

DOD is responsible for providing the military that secures the nation from external threats. Article II of the Constitution designates the President of the United States as Commander-in-Chief and grants the President authority over all US Armed Forces.3 Article I of the Constitution, however, grants Congress exclusive authority to declare war, raise armies, and establish rules for the military.4

The US Armed Forces, which became an all-volunteer force in 19735 consists of five service branches: the Army, Navy, Air Force, Marine Corps, and Coast Guard. All of the service branches are housed within DOD, except the Coast Guard which falls under the Department of Homeland Security during peacetime.

The Department of Veterans Affairs (VA) provides comprehensive medical care, educational opportunities, rehabilitation services, and numerous other benefits to veterans of the US Armed Services. The VA is separate from DOD and serves former members of the Armed Forces.

Policymakers and elected officials should be familiar with military culture, jargon, and the structure of the defense bureaucracy to perform their duties.

This military guide includes three sections:

  1. An introduction to DOD, including force size, structure, and roles of the five service branches;
  2. An overview of the VA and Veterans; and
  3. An explainer on common misconceptions about the US military and Veterans.

The Department of Defense is the federal department responsible for the supervision and coordination of the US Armed Forces.

The DOD has approximately 2.87 million personnel, divided between 2.15 million uniformed service members and 732,000 civilians. Additionally, the organization maintains 4,800 bases and facilities around the world and operates in more than 160 countries.6 DOD’s budget was $686 billion in Fiscal Year (FY) 2019. 7

DOD’s organizational structure consists of the Secretary of Defense, the Joint Chiefs of Staff, the US Armed Forces, nine Combatant Commands, and four national intelligence agencies. A description of each is below:

The Secretary of Defense 

The Secretary of Defense is a civilian cabinet official who oversees DOD and reports directly to the President. The Secretary is appointed by the President with the advice and consent of the Senate. The Secretary serves as the principal defense policymaker and is a member of the National Security Council (NSC).8 The Secretary also oversees the Office of the Secretary of Defense (OSD), which is the staff element responsible for policy development, planning, resource management, and program evaluation.9

The Joint Chiefs of Staff

The Joint Chiefs of Staff (JCS) are the highest-ranking members of the Armed Forces that advise the President, Secretary of Defense, and the NSC. The Service Chiefs advise and plan only and hold no command authority over the deployment of military personnel.10

The US Armed Forces

Since the elimination of the Draft in 1973,11 The US Armed Forces have been composed of volunteers. Approximately 2.15 million Americans currently serve in the US Armed Forces making military personnel roughly 1.5% of the age 18 to 55 general population. The US Armed Forces consist of five service branches: the Army, Navy, Air Force, Marine Corps, and Coast Guard.12

Each service branch has an active component of full-time service members and a reserve component of part-time service members. The reserve component of the US Armed Forces consists of the Reserves and National Guards. Reserve units are subordinate to the President and the federal government. National Guard units are subordinate to state governments and can only be called to federal service with consent from states. Reserve component personnel serve a minimum of one weekend a month and two weeks a year and can be called to active status to supplement full-time personnel.

The US Army

The US Army is the service branch responsible for land warfare. It conducts ground combat and is known for administering heavy ground combat equipment such as tanks and artillery cannons. The Army also possesses helicopters that provide airlift capabilities and close air support. The active component of the US Army boasts nearly a half-million service members and is the largest branch within the Armed Forces. 13

  • Number of Personnel: 483,500 active14 and 543,000 reserve component personnel15
  • Annual Budget: Approximately 178.9 billion (FY 2019)16

The US Navy

The US Navy is responsible for all combat that occurs on the high seas. The Navy maintains a fleet of vessels such as large battleships, submarines, and aircraft carriers. Additionally, the Navy operates a significant number of fixed-wing jetfighters, planes, and helicopters.

  • Number of Personnel: 337,121 active17 and 59,000 reserve component personnel18
  • Fleet Size: 290 ships and submarines19
  • Annual Budget: Approximately $195.7 billion (FY 2019)20

The US Marine Corps

The US Marine Corps is responsible for combat operations to secure beaches as well as conducting short-term combat operations with limited logistics support. The Marines make use of amphibious landing crafts, helicopters, jet fighters, and gunboats to accomplish its various missions. In addition to the Marines’ wartime mission, the organization is also responsible for the maintenance and operations of Marine One, which is the helicopter that carries the President. The Marines also provide security for US embassies, consulates, and other government offices.21 The Marines are a separate branch of the US Armed Forces, however, they report to the Department of the Navy.

  • Number of Personnel: 182,000 active22 and 38,500 reserve component personnel23
  • Annual Budget: The Marine Corps’ funding is included in the budget for the Department of the Navy

The US Air Force

The US Air Force is the aerial and space warfare service branch. Its missions include attacking ground assets from the air, maintaining control of airspace, and military airlift. The Air Force is also responsible for military operations in space such as the destruction of enemy satellites.24 Finally, it is responsible for Air Force One, which is the President’s official airplane.

  • Number of Personnel: 327,215 active duty25 and 176,400 reserve component personnel26
  • Number of Aircrafts: 5,047 manned aircrafts27
  • Annual Budget: Approximately $192.9 billion (FY 2019)28

The US Coast Guard 

The US Coast Guard is the coastal defense, maritime law enforcement, and maritime search and rescue branch. During peacetime, the US Coast Guard falls under the authority of the Department of Homeland Security. However, during war, the President can transfer all Coast Guard assets to the Department of the Navy.29

  • Number of Personnel: 56,000 active30 and 7,000 reserve component personnel31
  • Fleet Size: 1,843 boats and cutters32
  • Annual Budget: $11.65 billion (FY 2019)33 

Unified Combatant Commands

The US Armed Forces are organized into 10 Unified Combatant Commands (COCOMs), which provide command and control for military personnel regardless of branch. The purpose of the COCOMs is to promote coordination and cooperation between the service branches in the execution of their missions. Six geographic COCOMs are responsible for all seven continents. Additionally, there are four functional COCOMs34:

  • US Cyber Command is responsible for cyberspace operations;
  • US Strategic Command is responsible for strategic deterrence and the nuclear arsenal;
  • US Special Operations Command oversees Special Operations; and
  • US Transportation Command manages transportation assets.

The Rank Structures

The uniformed members of the US Armed Forces are made up of commissioned officers and enlisted personnel.35

Commissioned officers are uniformed DOD employees that hold a position of legal authority and act as managers for enlisted service members. These officers are responsible for planning military operations and leading service members during peacetime and war. There are multiple ways to receive a military commission, however, most officers are commissioned in one of three ways: attending a military service academy such as West Point or the Naval Academy, participating in a Reserve Officer Training (ROTC) Program at participating universities, or through a direct commission.36

Enlisted personnel are those that hold ranks below officers. These individuals make up the majority of the US Armed Forces and typically perform only those duties related to their specific role. Enlisted personnel serve in numerous and varied roles ranging from infantrywomen and men to biomedical engineers and everything in between. Some enlistees can be promoted to noncommissioned officer and supervise junior enlisted personnel on behalf of commissioned officers. 

DOD National Intelligence Agencies

In addition to the military intelligence professionals serving in the service branches, DOD also has authority over four national intelligence services:

  • The National Security Agency (NSA) specializes in cryptology and signals intelligence such as intelligence collected from computers and other digital communications platforms;37
  • The Defense Intelligence Agency (DIA) specializes in defense and military-specific intelligence;38
  • The National Geospatial-Intelligence Agency (NGA) is charged with collecting and analyzing imagery that depicts physical and geographical features on Earth;39 and
  • The National Reconnaissance Office (NRO) operates reconnaissance satellites and collects satellite intelligence on behalf of other national intelligence agencies.40

All four of DOD’s intelligence agencies are also members of the US Intelligence Community (IC). As such, they report to the Secretary of Defense and the Director of National Intelligence.41 

The Military Health System

The Military Health System (MHS) provides health care to active component military personnel, retirees, and their immediate families.42 A key component of the MHS is TRICARE, which is the health care program that provides comprehensive health coverage at no additional cost to service members. As part of TRICARE, active component service members, qualifying reservists, retirees, and dependents receive preventive care, emergency services, dental, behavior health, and a myriad of other health care benefits.43

The Department of Veterans Affairs provides various services to individuals who previously served in the US Armed Forces.

The VA manages programs designed for veterans and their families. The VA is most widely known for providing health services to qualified military veterans at VA centers and affiliate clinics. The VA also administers other benefits to veterans and, in some cases, their families, including education and training benefits,44 service-connected disability compensation, home loan guarantees, pensions, burial services, and other benefits.45 The VA is not a DOD entity; the VA is a cabinet-level agency overseen by the Secretary of Veterans Affairs.

The term “Veteran” is used to describe any individual who served any length of time in the US Armed Forces. Legally, however, a Veteran is any person who has served in the active component of the Armed Forces and was not dishonorably relieved of duty. Reserve component service members only receive veteran status if they serve at least 180 consecutive non-training days on active duty or have served for 20 years in the Reserve component.46 Military retirees are Veterans that have served honorably for 20 or more years or have been medically retired due to service-connected injuries. Unlike non-retired veterans, retirees also maintain access to many DOD services such as TRICARE, which provides members of the Armed Forces full health care coverage at no cost to the service member.47

There are a number of common misconceptions about the military and Veterans.

There are several common misunderstandings about the US military and Veterans that policymakers and their staff must be careful to avoid. These misconceptions include:

  • Everyone in the military serves in a combat role: Approximately 80% of the roles in the US Armed Forces are non-combat roles and translate to traditional civilian occupations.48
  • There aren’t many women that serve: As of 2018, women made up 16% of the enlisted corps, 18% of the officer corps of the US Armed Forces.49 Additionally, more than 2 million of the 21 million veterans are women.50
  • Everyone in the Air Force is a pilot: Only a select number of individuals in the Air Force are pilots. Many Airmen serve in fields that require no flying such as cybersecurity, logistics, and piloting drones.51
  • Everyone who has ever joined the military is a Veteran: Individuals that have previously served may be referred to as Veterans. Legally, however, only Active component service members that receive other than dishonorable discharges and certain Reservists receive Veterans status and are entitled to their benefits.52
  • All Veterans are Military Retirees: Only those individuals who have served honorably for at least 20 years or have been medically retired are considered Military Retirees.53
  • Veterans are prone to violence: Veterans aren’t any more prone to commit violence than the average citizen and veterans have lower incarceration rates than non-veterans.54 Veterans, however, are more likely to take their own lives than the general population.55
  • Everyone in the military carries a firearm. This is only true when service members are deployed in combat situations. Otherwise, uniformed service members are prohibited from carrying firearms in public unless they are training or they are Military Police. 
  • Everyone that serves is a Soldier: Soldiers serve in the Army, Airmen serve in the Air Force, Sailors serve in the Navy, and Marines serve in the Marine Corps. 
  • Everyone who joins the military enlists: There are three categories of service members: Commissioned Officers, Warrant Officers, and enlisted personnel. Only enlisted personnel “enlist,” however, it is the most common method of joining the military.56
  • Everyone who joins the military goes through basic training: Only individuals that enlist attend what is commonly known as basic training. Officers participate in branch-specific basic officer courses that focus on a different curriculum than basic training.
  • The NSC is part of DOD: The NSC is part of the Executive Office of the President, however, the Secretary of Defense sits on the NSC.57
  • Everyone who works for DOD is in the military: The DOD employs over 700,000 civilians, which serve in roles such as intelligence, policy development, logistics, and human resources.58
  • Ranks are the same between branches: Military paygrades are the same between branches, however, titles may vary between branches. For example, an Officer Grade 3 (O-3) in the Army, Air Force, and Marines is called a Captain. In the Navy and Coast Guard, however, an O-3 is called a Lieutenant and Captains equate to an O-6.59
  • The VA is part of DOD: The VA is a cabinet-level agency completely separate from DOD, however, the VA serves Veterans of the US Armed Forces.60
  • Only individuals that lack economic opportunity join the military: Most enlisted members of the military come from middle-income families. High-income families, however, are underrepresented in the military.61
  • VA healthcare is the same as TRICARE: TRICARE is only available to retirees, active members of the Armed Forces, and their families.62 VA health care is only available to Veterans of the Armed Services and, unlike TRICARE, typically includes additional costs such as copays.63


  1. Bialik, Kristen. “The Changing Face of America’s Veteran Population.” Fact Tank, Pew Research Center, 10 Nov. 2017,

  2. Kosiak, Steven. “Is the U.S. Military Getting Smaller and Older? And How Much Should We Care?” Center for a New American Security, 14 Mar. 2017,

  3. “Commander in Chief Powers.” Legal Information Institute, Cornell Law School,

  4. “War Powers.” Legal Information Institute, Cornell Law School,

  5. Glass, Andrew. “U.S. Military Draft Ends, Jan. 27, 1973.” 27 Jan. 2012. Politico,

  6. “Our Story.” United States Department of Defense,

  7. “FY 2019 Defense Budget.” United States Department of Defense,

  8. “Secretary of Defense.” United States Department of Defense,

  9. “Office of the Secretary of Defense.” United States Department of Defense,

  10. “About.” Joint Staff, Joint Chiefs of Staff,

  11. Glass, Andrew. “U.S. Military Draft Ends, Jan. 27, 1973.” 27 Jan. 2012. Politico,

  12. The US Coast Guard is one of the five branches of the Armed Services, however, it falls under the Department of Homeland Security during peacetime. During war, however, the President can transfer all Coast Guard assets to the Department of the Navy.

  13. Reynolds, George M. and Amanda Shendruk. “Demographics of the U.S. Military.” Council on Foreign Relations, 24 Apr. 2018,

  14. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  15. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  16. “National Defense Budget Estimates for FY 2020.” Office of the Under Secretary of Defense, May 2019,

  17. “Navy Personnel.” Status of the Navy, Navy, Oct. 8, 2019, Accessed 8 Oct. 2013.

  18. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  19. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  20. “National Defense Budget Estimates for FY 2020.” Office of the Under Secretary of Defense, May 2019,

  21. “What is MSG Duty.” Marine Corps Embassy Security Group, United States Marines,

  22. “Department of Defense (DoD) Releases Fiscal Year 2017 President’s Budget Proposal.” Department of Defense, 9 Feb. 2016,

  23. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  24. To date, no combat has occurred in Space. The missions of the US Space Force, the space warfare branch proposed by the Trump administration, is currently conducted by the US Air Force through US Air Force Space Command (AFSPC)

  25. “Air Force Demographics.” Air Force’s Personnel Center, United States Air Force, 2 July 2019,

  26. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  27. “World Air Forces 2018.” Flight International,

  28. “National Defense Budget Estimates for FY 2020.” Office of the Under Secretary of Defense, May 2019,

  29. “Our Forces.” United States Department of Defense,

  30. “The Coast Guard: America’s Oldest Maritime Defenders.” Go Coast Guard,

  31. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  32. National Defense Authorization Act for Fiscal Year 2018 (PL 115-91)

  33. “Posture Statement | 2019 Budget Overview | 2017 Performance Highlights.” United States Coast Guard,

  34. “Combatants Commands.” United States Department of Defense,

  35. There is a special class of officers known as Warrant Officers in the US Armed Forces. Warrant officers are positioned above enlisted personnel but below commissioned officers. Warrant Officers are proficient in a highly technical skill such as medical technology, mechanical engineering, or piloting, however, they do not typically hold positions with command authority.  The Air Force is the only branch of service that does not make use of Warrant Officers.

  36. “Becoming an Officer.” Today’s Military,

  37. “Mission & Values.” National Security Agency,

  38. “About DIA.” Defense Intelligence Agency,

  39. “About NGA.” National Geospatial-Intelligence Agency,

  40. “About NRO.” National Reconnaissance Office,

  41. “How the IC Works.” Office of the Director of National Intelligence,

  42. “About the Military Health System.” Military Health System,

  43. “About Us.” TRICARE, Defense Heath Agency, Military Health System,

  44. The Post 9/11 GI Bill is one of the major educational benefits provided to service members and veterans. The program provides funding for tuition, books, and housing. Use the following link for more information about the GI Bill:

  45. “U.S. Department of Veterans Affairs.”,

  46. Soucy, Jon. “Guard and Reserve Members Receive ‘Veteran’ Status.” National Guard Bureau,

  47. “TRICARE.” TRICARE, Defense Heath Agency, Military Health System,

  48. “5 Military Myths – BUSTED!” Military,com,

  49. “5 Military Myths – BUSTED!” Military,com,

  50. Bell, Jerri. “Five Myths About Female Veterans.” Washington Post,

  51. “Browse Careers.” United States Air Force,

  52. 38 USC 101(2). United States Code, US Government Publishing Office, 7 Jan 2011,

  53. “Types of Retirement.” Defense Finance and Accounting Service,

  54. “Veterans in Prison and Jail.” Bureau of Justice Statistics, Office of Justice Programs, 18 Jan. 2000,

  55. “Veterans and America’s Gun Suicide Crisis.” Giffords Law Center,

  56. Reynolds, George M. and Amanda Shendruk. “Demographics of the U.S. Military.” Council on Foreign Relations, 24 Apr. 2018,

  57. “National Security Council.” White House,

  58. “Our Story.” United States Department of Defense,

  59. A graphical break down of all ranks of the Armed Forces can be found here:

  60. “About VA.” United States Department of Veterans Affairs,

  61. Reynolds, George M. and Amanda Shendruk. “Demographics of the U.S. Military.” Council on Foreign Relations, 24 Apr. 2018,

  62. “About Us.” TRICARE, Defense Heath Agency, Military Health System,

  63. “The Affordable Care Act, VA, and You.” United State Department of Veterans Affairs,