United States Department of Defense
| United States Department of Defense | |
|---|---|
 26 July 1947 | |
| Headquarters | Pentagon Arlington, Virginia |
| Jurisdiction | United States Government |
| Budget | $534.3 billion (2016) |
| Personnel | |
| Active-duty military | 1,300,000 |
| Reserves | 826,000 |
| Civilian employees | 742,000 |
| Civilian Leadership | |
| Commander in Chief | President Donald Trump |
| Secretary of Defense | James Mattis |
| Deputy Secretary of Defense | Patrick M. Shanahan |
| Secretary of the Army | Mark Esper |
| Secretary of the Navy | Richard V. Spencer |
| Secretary of the Air Force | Heather Wilson |
| Military Leadership | |
| Chairman Joint Chiefs of Staff |
GEN Joseph Dunford |
| Chief of Staff Army |
GEN Mark A. Milley |
| Chief of Naval Operations | ADM John M. Richardson |
| Chief of Staff Air Force |
GEN David L. Goldfein |
| Commandant of the Marine Corps |
GEN Robert B. Neller |
The United States Department of Defense (DoD) is the government department in charge of managing matters involving military operations and national security. It was formerly known as the War Department. The current Secretary of Defense is James Mattis.
Technology
The DoD has developed significant technology that has been re-purposed for civilian use, such as the modern digital computer, the Internet, and the Global Positioning System. Artillery trajectories were calculated by "computers", that is, actual human beings who did the math by hand, until military necessity accelerated development of "electronic brains" such as the ENIAC (see also UNIVAC). The Internet was created and promoted by the Pentagon, largely because of the need to have redundant lines of communication to survive an enemy attack on phone and telegraph systems. The GPS satellites originally broadcast encrypted signals to support logistics, but a less precise signal is now also broadcast for hikers, taxi cab drivers, and commuters.
