U.S. Nuclear Weapons Complex: Overview of Department of Energy Sites [September 6, 2018] [open pdf - 1MB]
"Responsibility for U.S. nuclear weapons resides in both the Department of Defense (DOD) and the Department of Energy (DOE). DOD develops, deploys, and operates the missiles and aircraft that deliver nuclear warheads. It also generates the military requirements for the warheads carried on those platforms. DOE, and its semiautonomous National Nuclear Security Administration (NNSA), oversee the research, development, testing, and acquisition programs that produce, maintain, and sustain the nuclear warheads. To achieve these objectives, the facilities that constitute the nuclear weapons complex produce nuclear materials, fabricate nuclear and nonnuclear components, assemble and disassemble nuclear warheads, conduct scientific research and analysis to maintain confidence in the reliability of existing warheads, integrate components with nuclear weapons delivery vehicles, and conduct support operations."
CRS Report for Congress, R45306