In support of the presidential mandate, the Department of Energy's National Nuclear Safety Administration (NNSA) is responsible for ensuring the integrity and security of the United States' nuclear weapons, promoting nuclear non-proliferation, and international nuclear security. The NNSA works to ensure that the nation's nuclear weapons stockpiles are safe and secure, as well as the safety of naval nuclear reactors. In the event of a nuclear emergency, they are the first to respond and work on nuclear non-proliferation issues around the world. The International Atomic Energy Agency (IAEA) safeguards are an essential component of the international security system.
The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is a cornerstone of global efforts to prevent further spread of nuclear weapons. Under article 3 of the Treaty, each non-nuclear-weapon State is obliged to conclude a safeguards agreement with the IAEA. In 1939, President Franklin Roosevelt ordered the development of nuclear weapons during World War II due to fear of a race with Nazi Germany to develop such a weapon. The National Standards Office was initially in charge, but at the behest of British scientists and American administrators, it was transferred under the Office of Scientific Research and Development in 1942 and became known as the Manhattan Project.
This joint venture between the United States, Britain, and Canada was led by General Leslie Groves. The Manhattan Project built more than thirty different sites for research, production, and testing related to the manufacture of pumps. These included Los Alamos National Laboratory in Los Alamos, New Mexico under physicist Robert Oppenheimer; Hanford plutonium production plant in Washington; and Y-12 Homeland Security Complex in Tennessee. On January 1, 1947, the Atomic Energy Act of 1946 (McMahon Act) came into effect and officially handed over control of the Manhattan Project to the United States Atomic Energy Commission (AEC).
On August 15, 1947, the District of Manhattan was abolished. A summary table of each U. S. operational series can be found in the United States Nuclear Test Series.
The intellectual capacity acquired through Operation Paperclip during World War II enabled the United States to embark on an ambitious program of rocketry. One of its first products was rockets capable of containing nuclear warheads. The MGR-1 Honest John was developed in 1953 as a surface-to-surface missile with a maximum range of 15 miles (24 km). Due to its limited scope, its potential use was very limited (it could not threaten Moscow with an immediate attack).
During this same period, computerized early warning systems such as Defense Support Program were developed to detect incoming Soviet attacks and coordinate response strategies. Intercontinental ballistic missile (ICBM) systems were also developed that could deliver a nuclear payload over vast distances, allowing U. nuclear forces capable of attacking the Soviet Union from Midwest America. Short-range weapons including small tactical weapons were deployed in Europe such as nuclear artillery and portable special atomic demolition ammunition.
The development of submarine-launched ballistic missile systems allowed hidden nuclear submarines to covertly launch missiles at distant targets making it virtually impossible for the Soviet Union to successfully launch a first-strike attack on America without receiving a deadly answer. Improvements in warhead miniaturization in the 1970s and 1980s allowed for miRV missiles that could carry multiple warheads each targeted separately. This raised debate over whether these missiles should be based on constantly rotating railway tracks or heavily fortified silos (the latter was chosen). This made Soviet missile defenses economically unviable since each offensive missile would require between three and ten defensive missiles to counter them.
Other advances in weapons supply included cruise missile systems which allowed an aircraft to fire a long-range low-flying nuclear missile at a target from a relatively comfortable distance. Current U. delivery systems make virtually any part of Earth's surface within reach of its nuclear arsenal although ground-based missile systems have a maximum range of 10,000 kilometers (6,200 miles) less than worldwide its submarine forces extend their range from a coast 12,000 kilometers (7,500 miles) inland plus in-flight refueling of long-range bombers and use of aircraft carriers extends possible range virtually indefinitely. Since its inception, America's nuclear program has suffered accidents in various forms ranging from investigative experiments with individual victims such as Louis Slotin during Manhattan Project to dispersion of nuclear rain from Castle Bravo shooting in 1954 to accidents such as aircraft crashes carrying nuclear weapons launching nuclear weapons from aircraft losses of nuclear submarines and missile explosions with nuclear weapons (broken arrows). How close any these accidents came to becoming major disasters is matter technical and academic debate and interpretation. The United States is one of five declared nuclear-weapon states under NPT which it was original drafter and signatory on July 1 1968 ratified on March 5 1970 All NPT signatories agreed refrain from assisting proliferation nuclear weapons other states Nuclear warheads counted for deployed heavy bombers deployed undeployed SLBM launchers deployed undeployed heavy bombers Although fear arms race prompted many politicians scientists advocate some degree international control sharing nuclear weapons information many politicians members armed forces.