The United States Department of Defense (Defense Department, USDOD, DOD or DoD, initially the National Military Establishment (NME)) is the U.S. federal department allocated the largest level of budgetary resources and charged with coordinating and supervising all agencies and functions of the government relating directly to national security

National security

National security is the requirement to maintain the survival of the state through the use of economic, diplomacy, power projection and political power. The concept developed mostly in the United States of America after World War II...

 and the United States armed forces

United States armed forces

The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...

. The organization and functions of the DoD are set forth in Title 10

Title 10 of the United States Code

Title 10 of the United States Code outlines the role of armed forces in the United States Code.It provides the legal basis for the roles, missions and organization of each of the services as well as the United States Department of Defense...

 of the United States Code

United States Code

The Code of Laws of the United States of America is a compilation and codification of the general and permanent federal laws of the United States...

.

The DoD is the major tenant of The Pentagon

The Pentagon

The Pentagon is the headquarters of the United States Department of Defense, located in Arlington County, Virginia. As a symbol of the U.S. military, "the Pentagon" is often used metonymically to refer to the Department of Defense rather than the building itself.Designed by the American architect...

 building near Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, and has three main components: the Departments of the Army

United States Department of the Army

The Department of the Army is one of the three military departments within the Department of Defense of the United States of America. The Department of the Army is the Federal Government agency which the United States Army is organized within, and it is led by the Secretary of the Army who has...

, Navy

United States Department of the Navy

The Department of the Navy of the United States of America was established by an Act of Congress on 30 April 1798, to provide a government organizational structure to the United States Navy and, from 1834 onwards, for the United States Marine Corps, and when directed by the President, of the...

, and Air Force.