Also known as: DoD · DOD · Department of War · DoW · Pentagon
The U.S. executive department responsible for the armed forces, established in 1949 and headquartered at the Pentagon, and since 2025 also styled the "Department of War."
The Department of Defense (DoD) is the U.S. executive department that oversees the armed forces and national defense. It traces to the National Security Act of 1947, which created the National Military Establishment on September 18, 1947; that body was renamed the Department of Defense on August 10, 1949. The DoD is headquartered at the Pentagon in Arlington, Virginia, is led by the Secretary of Defense (a cabinet official confirmed by the Senate who reports to the President), and oversees the three military departments, the Army, the Navy, and the Air Force, which organize the Army, Navy, Marine Corps, Air Force, and Space Force. On September 5, 2025, an executive order authorized "Department of War" and "Secretary of War" as secondary titles alongside the primary names, so you will increasingly see the department referred to as the Department of War. Because only an act of Congress can formally change the name, "Department of Defense" and "Secretary of Defense" remain the legally official titles. For startups, the DoD is the ultimate customer behind most defense contracts, and its rules (DFARS, CMMC, ITAR flow-downs, and NDAA policy) drive the compliance and insurance obligations that come with selling to it.
Source: U.S. Department of Defense (defense.gov)
In practice, yes, as a secondary name. A September 5, 2025 executive order authorized "Department of War" and "Secretary of War" as additional titles, and the department and its agencies increasingly use them. But the change is not statutory: only an act of Congress can formally rename the department, so "Department of Defense" and "Secretary of Defense" remain the legally official titles.
The Department of Defense is the overarching executive department. It contains three military departments, the Army, the Navy (which includes the Marine Corps), and the Air Force (which includes the Space Force), which recruit, train, and equip the forces. The DoD sets policy and controls the budget authorized through the NDAA and appropriations.
Definitions are educational and may be modified by your specific policy language, endorsements, and state rules. For regulatory guidance, refer to the California Department of Insurance or the NAIC.
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