The
Department of Defense (
DoD,
USDOD, or
DOD) is an
executive branch department of the federal government of the United States charged with coordinating and supervising all agencies and functions of the government concerned directly with
national security and the
United States Armed Forces. The Department is also the largest employer in the world, with more than 2.13 million active duty servicemen and women as well as their support staff of civilian workers. Adding to the total is over 1.1 million National Guardsmen and Reservists from the four services, bringing the total to just over 3.2 million employees. It is headquartered at
the Pentagon in Arlington, Virginia, just outside of Washington D.C.