United States Department of Defense facts for kids
Seal of the Department of Defense
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Logo for the Department of Defense
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 An aerial view of the Pentagon |
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| Formed | 18 September 1947 (as National Military Establishment) |
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| Type | Executive Department |
| Jurisdiction | U.S. federal government |
| Headquarters | The Pentagon Arlington County, Virginia, U.S. 38°52′16″N 77°3′21″W / 38.87111°N 77.05583°W |
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| Annual budget | $842 billion FY2024 |
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| Child agencies |
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The United States Department of Defense (often called DoD or DOD) is a very important part of the U.S. government. Its main job is to manage and oversee the country's military forces. This includes the Army, Navy, Marines, Air Force, Space Force, and sometimes the Coast Guard.
The DoD also handles many related tasks and agencies. As of late 2022, it has over 1.4 million active-duty military members. It also oversees more than 778,000 National Guard and reserve personnel. Plus, there are over 747,000 civilians working for the DoD. This brings the total number of employees to over 2.91 million people.
The main office of the Department of Defense is located at The Pentagon in Arlington County, Virginia. This is just outside Washington, D.C.. The DoD's goal is to "provide the military forces needed to deter war and ensure our nation's security." This means they work to prevent wars and keep the country safe.
The leader of the Department of Defense is the Secretary of Defense. This person is a high-ranking official who reports directly to the president of the United States. The president is the top commander of the U.S. armed forces.
Under the Department of Defense, there are three main military departments:
- the Department of the Army
- the Department of the Navy
- the Department of the Air Force
The DoD also includes several national intelligence agencies. These include the Defense Intelligence Agency (DIA) and the National Security Agency (NSA). Other important agencies are the National Geospatial-Intelligence Agency (NGA) and the National Reconnaissance Office (NRO).
Other agencies under the Department of Defense include the Defense Advanced Research Projects Agency (DARPA). This agency works on new technologies for the military. The Defense Logistics Agency (DLA) helps supply the military. The Missile Defense Agency (MDA) works on protecting against missiles. All these agencies report to the Secretary of Defense.
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How the Department of Defense Started
The idea of a national military force in the U.S. began long ago. In 1774, before the Revolutionary War, the colonies started preparing for defense. In 1775, the Second Continental Congress created the Continental Army. Later that year, they also formed the Continental Navy and the Continental Marines.
Early Military Departments
When the U.S. government was first set up, Congress created the War Department in 1789. This department handled military matters. For a while, it even managed naval affairs. Then, in 1798, Congress created the Navy Department.
For many years, the leaders of the War Department and Navy Department reported directly to the president. But after 1949, all military departments became part of a larger defense organization.
Creating a Unified Defense System
After World War II, President Harry Truman wanted to create one unified department for national defense. He felt that having separate departments led to wasted money and conflicts. On July 26, 1947, President Truman signed the National Security Act of 1947. This law created the National Military Establishment (NME).
The NME officially started on September 18, 1947. James V. Forrestal became the first Secretary of Defense, leading this new organization. In 1949, the National Military Establishment was renamed the "Department of Defense." It then took over the three military departments (Army, Navy, and Air Force). The name change happened partly because "NME" sounded like "enemy."
In 1958, the Department of Defense Reorganization Act made the department's structure clearer. It gave the Secretary of Defense more control over the military departments. It also made the chain of command for military operations simpler. This law also created the Advanced Research Projects Agency, which is now known as DARPA.
How the Department of Defense is Organized
The Secretary of Defense is the head of the Department of Defense. This person is chosen by the president and approved by the Senate. The Secretary of Defense is the president's main helper for all things related to the DoD. They have authority over the entire department.
The Department of Defense includes several key parts:
- The Office of the Secretary of Defense (OSD)
- The Joint Chiefs of Staff (JCS) and the Joint Staff (JS)
- The Office of the Inspector General (DODIG)
- The Combatant Commands
- The Military Departments (Army, Navy, Air Force)
- Various Defense Agencies
Office of the Secretary of Defense (OSD)
The Office of the Secretary of Defense (OSD) includes the Secretary and their main assistants. Most of these staff members are civilians. OSD helps the Secretary of Defense create policies, plan, manage resources, and oversee programs. It also works with other U.S. government departments, foreign governments, and international groups. OSD also oversees many Defense Agencies.
Defense Agencies
OSD is in charge of many defense agencies. Some examples include:
- Department of Defense Education Activity (DoDEA), which runs schools for military children.
- Defense Advanced Research Projects Agency (DARPA), which develops new technologies.
- Defense Health Agency (DHA), which manages military healthcare.
- Defense Logistics Agency (DLA), which provides supplies and services.
- Defense Threat Reduction Agency (DTRA), which works to counter weapons of mass destruction.
National Intelligence Agencies
Some defense agencies are part of the United States Intelligence Community. These agencies gather important information for the country. They work under the Department of Defense but also coordinate with the Office of the Director of National Intelligence.
These agencies help national leaders and military planners. They also support and work with other intelligence groups like the Central Intelligence Agency (CIA). The DoD manages how the country collects signals intelligence (from electronic signals) and geospatial intelligence (from maps and images). It also builds and operates satellites for intelligence gathering.
- National Intelligence Agencies under the Department of Defense
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National Geospatial-Intelligence Agency
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National Reconnaissance Office
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Joint Chiefs of Staff
The Joint Chiefs of Staff (JCS) is a group of top military leaders. They advise the Secretary of Defense, the National Security Council, and the president on military matters. The JCS includes the chairman of the Joint Chiefs of Staff (CJCS) and the vice chairman. It also includes the top military leaders from the Army, Marine Corps, Navy, Air Force, and Space Force. The chief of the National Guard Bureau is also a member.
After a law called the Goldwater–Nichols Act in 1986, the Joint Chiefs of Staff no longer directly command troops. Instead, the chairman of the Joint Chiefs of Staff is the main military advisor to the president and the Secretary of Defense. The other members of the JCS give their advice through the chairman.
The chain of command for military operations goes from the president to the Secretary of Defense. Then it goes to the commanders of the Combatant Commands.
The Joint Staff (JS) is a group of military personnel from all services. They work at the Pentagon and help the chairman and vice chairman do their jobs.
Military Departments and Services
There are three main military departments within the Department of Defense:
- The Department of the Army, which includes the United States Army.
- The Department of the Navy, which includes the United States Navy and the United States Marine Corps.
- The Department of the Air Force, which includes the United States Air Force and the United States Space Force.
Each military department is led by its own secretary (like the Secretary of the Army). These secretaries are chosen by the president and approved by the Senate. They are in charge of organizing, training, and equipping their military forces. However, they report to the Secretary of Defense.
- Military Departments of the Department of Defense
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Department of the Air Force
- Military Services of the Department of Defense
Unified Combatant Commands
A unified combatant command is a military command that includes people and equipment from at least two military departments. These commands have a broad, ongoing mission. They are responsible for leading military operations. Almost all U.S. forces that are actively operating are under one of these commands.
When military operations are happening, the command goes from the president to the Secretary of Defense. Then it goes to the commanders of the Combatant Commands.
As of 2019, the U.S. has eleven Combatant Commands. Some are based on geography, meaning they cover a specific part of the world. Others are based on a global function, like special operations or transportation.
Examples include:
- U.S. Northern Command (USNORTHCOM) for North America.
- U.S. Central Command (USCENTCOM) for the Middle East.
- U.S. Strategic Command (USSTRATCOM) for nuclear operations.
- U.S. Special Operations Command (USSOCOM) for special forces.
- U.S. Cyber Command (USCYBERCOM) for cybersecurity.
Department of Defense Budget
The Department of Defense has a very large budget. In 2017, its spending was about 3.15% of the U.S. economy (GDP). It also made up about 38% of all military spending worldwide. This was more than the next seven largest militaries combined.
The DoD's budget makes up most of the U.S. government's "discretionary spending." This is money that Congress decides how to spend each year, rather than money that is already set aside for specific programs. In 2017, the DoD's budget was 15% of the total U.S. federal budget. It was 49% of all discretionary spending.
It's important to know that the DoD's budget does not include all military-related costs. For example, money for nuclear weapons research is in the Department of Energy's budget. Pensions for military retirees are handled by the Treasury Department.
In 2015, the DoD's budget was $585 billion. This was the largest budget of any federal agency. It was more than half of all the money the U.S. government spent that year on discretionary programs.
For the 2024 fiscal year, the proposed budget for the Department of Defense was $842 billion.
Laws Related to the Department of Defense
The way the Department of Defense is organized and what it does is set out in Title 10 of the United States Code. This is a collection of U.S. laws.
Other important laws related to the DoD include:
- 1947: National Security Act of 1947 - This law created the original defense organization.
- 1958: Department of Defense Reorganization Act - This law clarified how the department is run.
- 1986: Goldwater-Nichols Act of 1986 - This law changed the chain of command for military operations.
Images for kids
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How the Department of Defense is organized after the creation of the U.S. Space Force.
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An organizational chart of the Department of Defense from December 2013.
See also
In Spanish: Departamento de Defensa de los Estados Unidos para niños
- Arms industry
- Energy usage of the United States military
- List of United States military bases
- Nuclear weapons
- United States Department of Homeland Security
- United States Department of Veterans Affairs
