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R45306National Defense

The U.S. Nuclear Weapons Complex: Overview of Department of Energy Sites

Federal & State Law Editorial TeamLast reviewed: July 2026
September 6, 2018

Summary

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 semi-autonomous 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.

The Trump Administration, in testimony before Congress and in the 2018 Nuclear Posture Review (released in February 2018), has raised concerns about the aging infrastructure of facilities in the nuclear weapons complex. While the Obama Administration proposed, and Congress funded, budget increases for these facilities in the past decade, the Trump Administration has argued that “the United States has not pursued the investments needed to ensure that the infrastructure has the capacity to not only maintain the current nuclear stockpile but also to respond to unforeseen technical or geopolitical developments.”

The nuclear weapons complex—what NNSA currently refers to as the Nuclear Security Enterprise—consists primarily of nine government-owned, contractor-operated sites in seven states, and a Tennessee Valley Authority (TVA) nuclear reactor used to produce tritium for nuclear weapons. The complex began with the establishment of the Manhattan Engineer District in 1942, then grew in size and complexity during the Cold War, before evolving into the current configuration during the 1990s.

Facilities at the current nine sites include three laboratories, five component fabrication/materials production plants, one assembly and disassembly site, a geologic waste repository, and one testing facility that now conducts research but was previously the location for U.S. underground nuclear tests. This report summarizes the operations at each of these sites.

As Congress conducts oversight of DOE’s and NNSA’s management, operations, and programs, and as it authorizes and appropriates funds for the Nuclear Security Enterprise, it may address a wide range of issues related to the nuclear weapons complex. These include questions about organization and management at NNSA, infrastructure recapitalization, plutonium pit production, and concerns about access to necessary supplies of tritium.

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Note: CRS reports are prepared for Members of Congress and their staffs. This summary is provided for informational purposes and does not constitute legal advice.

This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.