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Prevent, Counter, and Respond
Read about NNSA's efforts to prevent nuclear proliferation.

Preventing nuclear weapons proliferation and reducing the threat of nuclear and radiological terrorism around the world are key U.S national security strategic objectives that require constant vigilance.

NNSA's Office of Defense Nuclear Nonproliferation works globally to prevent state and non-state actors from developing nuclear weapons or acquiring weapons-usable nuclear or radiological materials, equipment, technology, and expertise.

Read more about the office's work in the DNN Sentinel.

NNSA's nonproliferation news and press releases

This is executed through the following strategic activities:

Global Material Security
Office of Radiological Security (ORS)
Learn how NNSA protects radioactive sources worldwide.
NNSA's Nuclear Smuggling Detection and Deterrence office aids countries by helping install radiation monitors at borders and entry points
Trucks pass through radiation portal monitors along Bulgaria’s border with Romania. The monitors allow automated, 24-hour screening of traffic at points-of-entry, detecting the presence of radiation in persons, vehicles, and cargo.   

The mission of the Office of Global Material Security (GMS) is to prevent terrorists from acquiring nuclear or radiological material that could be used in an attack on the United States, its interests, or allies. GMS works with partners worldwide to secure nuclear and radiological material and to detect and deter trafficking of this material.

There is enough nuclear material around the world to make tens of thousands of nuclear weapons, and there are large quantities of radioactive material that could be used in a radiological dispersal device or “dirty bomb.” The detonation of such a device could cause death, injuries, widespread panic, and mass evacuations.

GMS protects the United States by working overseas to provide partners with the capacity to secure nuclear and radiological material and stop smuggling efforts. Domestically, GMS helps partners secure and eliminate radiological materials to prevent their theft and use against the homeland.

International Nuclear Security

Works with international partners to improve nuclear material security by supporting training and training centers for security professionals, including national regulators and responders; developing nuclear infrastructure and regulations; and enhancing security systems. Read more about International Nuclear Security. 

Radiological Security

Works with government, law enforcement, and businesses across the globe to protect radioactive sources used for medical, research, and commercial purposes; remove and dispose of disused radioactive sources; and reduce the reliance on high-activity radioactive sources through the promotion of viable non-radioisotopic alternative technologies.

Read more about Radiological Security.

Nuclear Smuggling Detection and Deterrence

Works with international partners to strengthen capabilities to deter, detect, and investigate the smuggling of nuclear and radiological materials by providing the expertise and tools needed to respond to smuggling events.

Read more about Nuclear Smuggling Detection and Deterrence.

Material Management and Minimization
The molybdenum-99 (Mo-99) purification process
An Argonne National Laboratory chemist works to improve the molybdenum-99 (Mo-99) purification process. Mo-99 is an important medical isotope.

The most difficult step in the development of an improvised nuclear device is acquiring weapons-usable nuclear material. NNSA’s Material Management and Minimization program reduces the risk of highly enriched uranium (HEU) and plutonium falling into the hands of non-state actors by minimizing the use of and, when possible, eliminating weapons-usable nuclear material around the world.



The first step to minimizing the use of nuclear material is to eliminate the need. NNSA accomplishes this through the Convert Program, which works with civilian research reactors and medical isotope production facilities domestically and internationally.

Facilities that use weapons-usable material cooperate with NNSA and experts from the National Laboratories to convert their HEU fuel and targets to low-enriched uranium (LEU), a material that cannot be used in a nuclear weapon. NNSA also relies on the experts from the National Laboratories to develop and qualify new LEU fuels for some of the most complicated reactors around the world that have not yet been converted from HEU fuel.

As part of its HEU minimization mission, NNSA leads the molybdenum-99 (Mo-99) program. Mo-99 is an isotope that is used in over 40,000 medical procedures in the United States each day, but is 100 percent supplied by foreign vendors, most of which use HEU in the production process. The decay product of Mo-99, technetium-99m (Tc-99m), is the most commonly used radioisotope, relied upon for performing heart stress tests, identifying cancer throughout the body, and studying organ structure and function.


Once civilian partners eliminate the need for weapons-usable nuclear material, NNSA works with international partners and facilities to remove or dispose of excess HEU and separated plutonium. NNSA’s Remove Program relies on nuclear material technical experts across the National Laboratories to collaborate with international partners on the packaging of material so that it can be safely and securely returned to its country of origin (most commonly the United States and Russia) and/or dispositioned.

NNSA also maintains a capability to respond quickly in case material needs to be removed from a country of concern. The Emerging Threats program allows NNSA to bring all of the necessary tools into a foreign country to safely package and remove the material in a much shorter timeframe than is usually required.


After weapons-usable nuclear material is removed, any material that is brought back to the United States falls under the purview of NNSA’s Dispose Program, the primary mission of which is to disposition 187 MT of HEU and 34 MT of plutonium declared excess to national defense needs. NNSA downblends HEU with natural uranium to make LEU, which can be used by the Convert Program for research reactor fuel or isotope production targets. Resultant LEU can also support the American Assured Fuel Supply and NNSA’s Defense Program’s tritium production. By making LEU available for a variety of uses, the Dispose Program closes the material management cycle that began with the Convert and Remove Programs.

Fact sheets:

Nonproliferation and Arms Control

NNSA’s Office of Nonproliferation and Arms Control (NPAC) strengthens nonproliferation and arms control regimes to prevent proliferation, ensure peaceful nuclear uses, and enable verifiable nuclear reductions.

NPAC works to close proliferation pathways to the acquisition of nuclear weapons and weapons of mass destruction (WMD)-related materials, technology, and expertise by executing programs that:

  • build the capacity of the International Atomic Energy Agency (IAEA) and Member States to detect and deter diversion of nuclear material or illicit use of nuclear facilities;
  • build domestic and global capacity to control illicit trafficking of nuclear and WMD-related material and technology;
  • develop technologies and implement approaches to monitor and verify compliance; and
  • develop cross-cutting policy, programs and strategies to address enduring and emerging challenges to the nonproliferation regime.

International Nuclear Safeguards

NNSA’s International Nuclear Safeguards program builds the capabilities of the IAEA and partner countries to implement safeguards obligations. International nuclear safeguards are technical measures used to verify a country is in compliance with its legal agreements with the IAEA and not diverting nuclear material to weapons programs or pursuing undeclared nuclear activities. An effective and efficient safeguards system also requires the cooperation of Member States with capable safeguards regulatory authorities.

NNSA meets this mission by developing and implementing new safeguards concepts, approaches, and technologies. Additionally, the program coordinates the implementation of IAEA safeguards at U.S. Department of Energy facilities and fulfills the legislative mandate to ensure that U.S.-obligated nuclear material held in foreign countries is adequately protected.

Some basics on nuclear safeguards:

Nuclear Export Controls

NNSA’s Nuclear Export Controls program facilitates legitimate civil nuclear cooperation by strengthening domestic and global capacity to detect and prevent illicit or unintended transfers of WMD-related materials, equipment, and technology to destinations of concern.  NNSA does this through programs that: strengthen the U.S. Government’s ability to prevent and interdict transfers that would contribute to foreign WMD programs of concern; strengthen foreign partner national systems of export control; and strengthen multilateral export control regimes.  Further, NNSA is part of the interagency licensing review process to ensure that thousands of proposed exports of sensitive items or technologies receive the appropriate level of scrutiny before being transferred.

While some nations and terrorist groups are working to obtain nuclear and radiological materials, equipment, and technologies to build WMD’s, many of the resources needed for their manufacture are “dual-use” in nature, with legitimate civil and military applications.  They have important uses in clean energy, modern medicine, advanced imaging techniques, sterilized equipment, and other applications.

NNSA strengthens the capacity of U.S. government agencies to prevent and interdict U.S.-origin transfers by providing customized WMD commodity identifications training to targeting and inspection specialists, enforcement, and investigative agencies.  NNSA also engages foreign partners to strengthen their national export control systems to prevent illicit trafficking in nuclear and dual-use items through customized export licensing, enterprise outreach, and enforcement training programs, with the goal of developing a cadre of export control experts to provide training through bilateral and international partnerships.

Nuclear Verification

Developing and maintaining the technical means to monitor whether the terms of a nuclear arms control treaty or other international agreement are fulfilled is a critical factor in ensuring that such agreements are successful.

NNSA’s Office of Nuclear Verification (ONV) plays a vital role supporting the development and implementation of arms control treaties, government-to-government agreements focused on nuclear weapon limitations, and the preparation for and implementation of nuclear weapons materials reduction verification and monitoring activities with foreign partners.  Additionally, ONV maintains both human and technical resources that permit rapid deployment to locations worldwide where U.S.-led on-site verification and/or monitoring activities are required. 

Nonproliferation Policy

NNSA’s nonproliferation policy function develops policies, programs, and strategies to reduce nuclear dangers; addresses emerging challenges and opportunities in nonproliferation and arms control; and supports the implementation of bilateral, multilateral, President-directed, or congressionally mandated nonproliferation and international security initiatives, agreements, and treaties. These capabilities support NPAC’s core competency areas—international nuclear safeguards, nuclear export controls, and nuclear verification. This overarching and cross-cutting policy function also informs NNSA and DOE, and supports the interagency and U.S. participation in multilateral organizations.

Research and Development
Workers conduct a Source Physics Experiment at the Nevada National Security Site.
Workers at Nevada National Security Site prepare for a Source Physics Experiment to improve U.S. capability to detect and characterize underground nuclear explosions and help develop capability for monitoring low-yield nuclear testing.

NNSA advances its nuclear threat reduction mission by developing ways to detect and monitor foreign nuclear fuel cycle and weapons development activities, special nuclear material movement or diversion, and nuclear explosions. These same capabilities support nuclear arms control treaty monitoring and verification, operational interdiction and other nuclear security efforts across NNSA and the U.S. Government. This includes delivering space-based sensors to meet the nation’s operational nuclear test treaty monitoring obligations as well as its need to warn and give assessments of air, missile, and space threats. It also includes improving the speed, accuracy, confidence, and specificity of nuclear forensics analytic capabilities related to nuclear detonations.

Using the unique facilities and scientific skills of NNSA and Department of Energy’s national laboratories, and in partnership with industry and academia, R&D efforts provide the technical base for national and homeland security agencies to meet their nonproliferation, counterproliferation, and counterterrorism responsibilities.