possessors, and (3) various types of monitoring by which the other parties can confirm that the declarations are correct and complete. This basic architecture for verification built upon transparency and monitoring applies whether the focus is a few containers of nuclear-explosive material or an extensive nuclear stockpile containing thousands of intact weapons and components and many tons of NEM.
Interest in the possible benefits of increased transparency and monitoring has long been limited by two widely held suppositions. The first is that it is simply not technically feasible under present and foreseeable circumstances to verify numbers of nuclear weapons themselves (as opposed to number of delivery systems)—and even less to verify stockpiles of NEM. The second is that any attempt to address the difficulty of significantly increasing transparency about nuclear weapons and NEM would necessarily collide with critical national security needs to protect nuclear weapon secrets. We have attempted in this study to understand and clarify the extent to which these suppositions are in fact valid. We have done so by assessing the challenges for transparency and monitoring for the numbers and status of nuclear weapons and quantities of NEM, the state of the art in technological and institutional approaches for addressing these challenges, and the prospects for improving the state of the art—not only through creating new technologies but also through combining existing technological and institutional capabilities more effectively.
As a result of this assessment we have come to the following general conclusions:
Current and foreseeable technological capabilities exist to support verification at declared sites, based on transparency and monitoring, of declared stocks of all categories of nuclear weapons—strategic and nonstrategic, deployed and nondeployed—as well as for the nuclear-explosive components and materials that are their essential ingredients. Many of these capabilities could be applied in existing bilateral and international arrangements without the need for additional agreements beyond those currently in force.
There are some tensions between sharing information about nuclear weapon and NEM stockpiles and maintaining the security of these stockpiles, but cooperative use of available and foreseeable technologies can substantially alleviate these tensions.
The nature of NEM production and the characteristics of NEM and nuclear weapons place some fundamental limits