Original: The United States Department of Defense ( USDOD , DOD or DoD , initially briefly referred to as the National Military Establishment or NME ) is the U.S. federal department charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the United States armed forces .
Simplified: The United States Department of Defense , also known as the DoD , is a department in the United States government that is in charge of the military of the United States .