The Department of Defense is a Cabinet-level federal agency formed to consolidate the departments of the armed services after World War II. Its principal responsibility is the operation of the military services for national defense.

In 2025, President Donald Trump issued an executive order authorizing the Department of Defense and the Secretary of Defense to use the alternate titles “Department of War” and “Secretary of War” and directing the Secretary of Defense to report on what Congressional and other governmental actions would be required to formally re-designate the Department of Defense as the Department of War.¹

1. “Restoring the United States Department of War.” The White House, September 5, 2025. https://www.whitehouse.gov/presidential-actions/2025/09/restoring-the-united-states-department-of-war/.