From Absence Measurements To Verified Dismantlement Of Nuclear Weapons

Arms-control agreements between the United States and Russia negotiated after the end of the Cold War have imposed limits on the number of deployed strategic nuclear weapons. It is widely believed that future arms-control agreements, either bilateral or multilateral, would place limits on all weapons in the stockpiles, including those in storage or slated for dismantlement, so that the growing gap between existing weapons and those captured by arms-control regimes can be closed. Verification of such “all-warhead” agreements is likely to face some fundamentally new and complex challenges and may require new verification technologies and approaches to nuclear inspections. This paper examines three types of monitoring regimes that could be used to verify such agreements: the absence regime, the limited-access regime, and the confirmation regime. These regimes can build on each other, and they can be gradually phased in. In an absence regime all items are accepted as treaty accountable that the host declared as such. Inspected are only other items present at a site to confirm that they are indeed not accountable. The limited-access regime builds on the absence regime, but serial numbers or unique identifiers are used to identify declared items. While containment & surveillance technologies can play an important role to support such a regime, the authenticity of the warheads themselves is not confirmed. Only the third monitoring regime, the confirmation regime, envisions measurements to confirm the authenticity of declared nuclear weapons prior to dismantlement. The confirmation regime provides the highest confidence in the correctness of declared inventories and reductions. Several types of radiation measurement systems have been proposed for confirmation measurements, but the authentication and certification of information barriers has proven difficult so far. While research and development on these technologies continues, all-warhead agreements can be verified using absence or limited-access regimes, where technology gaps are small. As warhead inventories reach numbers that are significantly lower than those today, additional confidence in the correctness (and completeness) of declared warhead inventories may be required and confirmation measurements then be considered essential.