The mission of the Office of Counterterrorism and Counterproliferation is to counter these threats through innovative science, technology, and policy-driven solutions. The office is charged with understanding nuclear threat devices (i.e., improvised nuclear devices, foreign nuclear weapons of a proliferant concern, and any device that may have fallen outside of a foreign state’s custody). By leveraging this unique technical knowledge base, the Office of Counterterrorism and Counterproliferation provides the expertise, practical tools, and technically informed policy recommendations required to advance U.S. nuclear counterterrorism and counterproliferation objectives. Specifically, it executes a number of specialized programs and activities, including: implementing international nuclear security and counterterrorism dialogues; conducting technical and scientific activities to characterize, detect, and defeat nuclear threat devices; developing and conducting WMD counterterrorism tabletop exercises; and promoting nuclear information security policy and practices. The Office is also charged with mission coordination and management of a wide range of counterterrorism and counterproliferation contributions across NNSA organizations.