The Secretary of Defense is a high-ranking official in the United States government responsible for overseeing the Department of Defense and coordinating national security policies. This position plays a crucial role in shaping military strategy and ensuring the readiness of the armed forces, including the Army, Navy, Air Force, and Marine Corps. Appointed by the President, the Secretary of Defense advises on defense matters and represents the military in the Cabinet. This role is vital for maintaining the country's defense posture and managing relationships with international allies and adversaries, ensuring the safety and security of the nation.