The Nuclear Security Enterprise (NSE) mission is to ensure the Nation sustains a safe, secure, and effective nuclear deterrent through the application of science, technology, engineering, (ST&E) and manufacturing. In the next 20 years, the U.S. nuclear weapons stockpile will be sustained and modernized through vigorous surveillance, assessment, life extension and dismantlement efforts. In addition, progress will be made in modernizing the physical infrastructure that will evolve from a post-World War II/Cold War era nuclear weapons complex into a more efficient 21stcentury NSE with less environmental impact. To deal with the changing face of nuclear deterrence and more-widely dispersed nuclear knowledge, the Office of Defense Programs (DP) also ensures the United States maintains excellence in nuclear science and technology that is second to none. This central mission is referred to as Stockpile Stewardship and Management. The DP office utilizes an overarching guide for execution of NSE mission with the annual Stockpile Stewardship and Management Plan (SSMP).
The SSMP is DP’s program of record and is fundamentally an action plan with near term and strategic goals. The SSMP continues NNSA’s commitment to the objectives of the 2010 Nuclear Posture Review  and responds to the Congressional requirement for information about DOE activities that support the stockpile. The SSMP describes the overarching 20-year plan to accomplish the mission in accordance with national security policy guidance as follows:
- Ensure the U.S. nuclear weapons stockpile remains safe, secure, and effective
- Sustain and modernize the stockpile without conducting underground nuclear tests
- While developing and implementing Life Extension Programs (LEPs), use only nuclear components that are based on previously tested designs and provide no new military capabilities
- Study options for ensuring the safety, security, and reliability of nuclear warheads on a case-by-case basis, consistent with the Congressionally mandated Stockpile Management Program
- Consider the full range of LEP approaches, including refurbishment of existing warheads, reuse of nuclear components from different warheads, and replacement of nuclear components
- Give preference to options for refurbishment or reuse when considering any decision to proceed to engineering development of warhead LEPs
- Replace nuclear components only if critical Stockpile Management Program goals cannot otherwise be met and only if specifically authorized by the President and approved by Congress
- Strengthen the ST&E base that is vital for stockpile stewardship and provides insights in aid of nonproliferation efforts
- Refurbish and modernize the physical infrastructure that is required to ensure the long-term safety, security, and reliability of the nuclear arsenal.