Fact Sheet
Bureau of Arms Control, Verification and Compliance
December 18, 2012

Key Point: The Annual Assessment process of the U.S. Nuclear Weapons Stockpile is the authoritative method for the Department of Defense (DoD) and the Department of Energy’s National Nuclear Security Administration (DOE NNSA) to evaluate the safety, reliability, performance and military effectiveness of the nuclear weapons stockpile, and it is a principal factor in our ability to maintain a credible nuclear deterrent without nuclear explosive testing.

In 1995, President Clinton established an annual reporting and certification requirement that ensures the nation’s nuclear weapons remain safe and reliable without underground nuclear explosive testing. Subsequently, Congress enacted into law the requirement for annual stockpile assessments in Section 3141 of the National Defense Authorization Act for Fiscal Year 2003.

The Directors of the three DOE nuclear weapons laboratories—Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), and Sandia National Laboratories (SNL)—are required to complete annual assessments of the safety, reliability, and performance of each weapon type in the nuclear weapons stockpile. In addition, the Commander of U.S. Strategic Command provides an assessment of the military effectiveness of the stockpile. These assessments also include a determination as to whether it is necessary to conduct an underground nuclear test to resolve any identified issues. The Secretaries of Energy and Defense are required to submit these reports unaltered to the President, along with any conclusions the Secretaries consider appropriate.

The Annual Assessment Reports evaluate all relevant information on each system, and include analysis of nuclear weapon safety and security, and performance changes that would affect military effectiveness. This effort uses all available sources of information on each weapon type, including data from non-nuclear hydrodynamic tests, subcritical experiments, materials evaluation, enhanced surveillance activities, and supercomputer calculations.

The Annual Assessment process has evolved significantly since the inception of the Stockpile Stewardship Program in the mid-1990s, due to significant improvements in the tools and methods available. NNSA now places much greater emphases both on computational simulation and on understanding fundamental physical phenomena in weapons evaluation methods. In 2006, NNSA modified the surveillance program to be more requirements-based, with a focus on filling knowledge gaps and better understanding how the systems are aging. The NNSA has analyzed historical surveillance data for baseline “as deployed” characteristics for comparison to the current condition of warheads. This information helps to inform our understanding of how the stockpile is changing over time with respect to safety, reliability and security characteristics.