An amendment to the <a href="https://en.wikipedia.org/wiki/National_Security_Act_of_1947" id="mw8w" rel="mw:WikiLink" title="National Security Act of 1947">National Security Act of 1947</a> enhances the authority of the <a href="https://en.wikipedia.org/wiki/United_States_Secretary_of_Defense" id="mw9A" rel="mw:WikiLink" title="United States Secretary of Defense">United States Secretary of Defense</a> over the Army, Navy and Air Force, and replaces the National Military Establishment with the <a href="https://en.wikipedia.org/wiki/United_States_Department_of_Defense" id="mw9Q" rel="mw:WikiLink" title="United States Department of Defense">Department of Defense</a>.