What would become the nuclear security enterprise began in 1943, as the U.S. Army oversaw the construction of the first atomic weapons during the Manhattan Project. At that time, the majority of this work occurred in Los Alamos, New Mexico; Oak Ridge, Tennessee; and Hanford, Washington.
Following the end of World War II, President Harry Truman transferred the control of atomic energy from the military to the Atomic Energy Commission (AEC), a government agency. As the Cold War became a reality, the nuclear security enterprise grew to keep pace with the demand for nuclear weapons production. The locations for sites were often chosen with certain factors in mind: they usually avoided populated areas, offered sufficient resources (such as land and electricity), and were inland areas less vulnerable to attack. Politics also often influenced where facilities were built.
Since the end of the Cold War, the number of sites involved in nuclear weapons production has declined, as the United States has reduced the number of weapons in its stockpile while maintaining the capability to sustain the remaining nuclear weapons.
Today, the National Nuclear Security Administration (NNSA), a semiautonomous federal agency within the Department of Energy, manages seven of the eight government-owned, contractor-operated sites that comprise the modern nuclear security enterprise. (The Savannah River Site, which is currently overseen by the Department of Energy's Office of Environmental Management, will come under NNSA management in 2025.)
These sites, which include Los Alamos National Laboratory, are responsible for the research, development, testing, and acquisition programs that produce, maintain, and sustain nuclear weapons.
NNSA also works closely with the Department of Defense, which generates the military requirements for nuclear weapons, and develops, deploys, and operates the missiles and aircraft that deliver the weapons. ★