As states move to lower numbers of nuclear weapons and need the ability to detect and monitor smaller items and quantities of nuclear material, verification will become a more complex chal- lenge. The full lifecycle—from material inventories, warhead assembly, and deployment to storage, dismantlement, and disposition—will eventually have to be monitored and verified, a task that will be extremely difficult if inspectors do not have detailed records of a state’s total warhead and weapons-usable material inventory. Such records will take time to develop, and there are currently no agreed on mechanisms for recording, sharing, or verifying this information. Verifiable baseline declarations will be essential to filling this gap.
Carlson, John, James Fuller, Kelsey Hartigan, Matthew Bunn, et al. "Verifying Baseline Declarations of Nuclear Warheads and Materials." Report for the Nuclear Threat Initiative, July 2014.