The Committee on Armed Services, sometimes abbreviated SASC for Senate Armed Services Committee, is a committee of the United States Senate empowered with legislative oversight of the nation's military, including the Department of Defense, military research and development, nuclear energy, benefits for members of the military, the Selective Service System and other matters related to defense policy. The Armed Services Committee was created as a result of the Legislative Reorganization Act of 1946 following the U.S. victory in World War II. The bill merged the responsibilities of the Committee on Naval Affairs, established in 1816, and the Committee on Military Affairs, also established in 1816.

The United States Department of Defense is an executive branch department of the federal government of the United States charged with coordinating and supervising all agencies and functions of the U.S. government directly related to national security and the United States Armed Forces. As of June 2022, the U.S. Department of Defense is the largest employer in the world, with over 1.34 million active-duty service members, including soldiers, marines, sailors, airmen, and guardians. The Department of Defense also maintains over 778,000 National Guard and reservists, and over 747,000 civilians bringing the total to over 2.87 million employees. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the Department of Defense's stated mission is to provide "the military forces needed to deter war and ensure our nation's security".