United States Department of Defense
The U.S. federal executive department that coordinates and supervises the armed forces and directs national defense policy.
Secretary of Defense: The civilian head of the Department of Defense and the principal defense adviser to the president. This office exercises civilian leadership over the department and armed forces.
National Command Authority: The U.S. president and Secretary of Defense acting through the lawful chain of command over the armed forces. This authority governs operational orders from civilian leaders to combatant commands.
National Security Act of 1947: U.S. legislation that created the National Military Establishment and established major postwar national-security institutions. It laid the institutional foundation for the department.
United States military budget: Federal spending allocated to U.S. military forces and defense activities, principally through Department of Defense appropriations. Its budget funds personnel, operations, equipment, and research.
Military–industrial complex: The network of relationships among a country's armed forces, defense industries, and political institutions. The department's procurement and budget decisions help shape this network in the United States.
Joint Chiefs of Staff: A group of senior military leaders who advise civilian officials but do not command operational forces. The chiefs advise on military matters while operational command follows a separate chain.
Goldwater–Nichols Act: The 1986 U.S. law that reorganized military command and strengthened the role of joint operations. It clarified command relationships and elevated combatant commanders.
National Security Act Amendments of 1949: Legislation that renamed the National Military Establishment the Department of Defense and strengthened the Secretary's authority. These amendments created the department under its present name.
Defense acquisition: The process of developing, purchasing, and sustaining military systems and services. The department uses acquisition programs to equip its forces.
United States defense industry: Companies that produce military equipment, technology, and services for the U.S. government and other customers. Department contracts make it a central customer and influence industrial capacity.