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 the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, and over 742,000 civilians bringing the total to over 2.8 million employees. It is headquartered at the Pentagon in Arlington, Virginia, just outside Washington, D.C.

Answer this question based on the passage: which branch of government commands the army and navy? OK. Let's think. My stream of consciousness:
The important part for answering this question is: 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 answer is executive branch.