The United States Department of Energy (DOE) is a Cabinet-level department of the United States government responsible for energy policy and nuclear safety. Its purview includes the nation's nuclear weapons program, nuclear reactor production for the United States Navy, energy conservation, energy-related research, radioactive waste disposal, and domestic energy production. DOE also sponsors more basic and applied scientific research than any other US federal agency, most this is funded through its system of United States Department of Energy National Laboratories.
In the United States, all nuclear weapons deployed by the US Department of Defense (DOD) are actually on loan to DOD from the DOE, which has federal responsibility for the design, testing and production of all nuclear weapons. DOE in turn uses contractors to carry out its responsibilities; design of the nuclear components of the weapon - Los Alamos National Laboratory and Lawrence Livermore National Laboratory, engineering of the weapon systems - Sandia National Laboratory, manufacturing of key components - Los Alamos National Laboratory, testing - Nevada Test Site, and final weapon/warhead assembling/dismantling - Pantex.
Many federal agencies have been established to handle various aspects of U.S. energy policy, dating back to the creation of the Manhattan Project and the subsequent Atomic Energy Commission. The impetus for putting them all under the auspices of a single department was the 1973 energy crisis, in response to which President Jimmy Carter proposed creation of the department. The enabling legislation was passed by Congress and signed into law by President Carter on August 4, 1977. The department began operations on October 1, 1977. The agency is administered by the United States Secretary of Energy, and its headquarters are located in Germantown, Maryland as well as southwest Washington, D.C., on Independence Avenue in the Forrestal Building, named for James Forrestal.

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