The Defense Department, officially known as the Department of Defense (DoD), is a United States government agency responsible for coordinating and supervising national security and military policies. It oversees the armed forces, including the Army, Navy, Air Force, and Marine Corps, ensuring they are prepared to defend the country against threats. Established in 1947, the Defense Department plays a crucial role in formulating defense strategies and managing military operations. It also works closely with other government agencies and international partners to promote global security and stability, addressing issues such as terrorism and cyber threats.