sentences:  The origin of the Air Force Nuclear Weapons Center began during the post-World War II following the Manhattan Project, which was designed by the United States Army from the outset to be a temporary organization to produce a nuclear weapon.With the end of the war, the establishment of the "Z Division" at Sandia Base and later the Sandia National Laboratory led to the creation of a United States Army Air Forces organization to coordinate military activities with the civilian research organization in 1946.On September 18, 1947, President Harry S. Truman signed the National Security Act of 1947, separating the Army Air Forces from the Army by creating the independent United States Air Force.