Notes
The author gratefully acknowledges research support from Harvard University's Belfer Center for Science and International Affairs at the John F. Kennedy School of Government and the Nuclear Threat Initiative. The author also appreciates helpful comments from Graham Allison, Wilhelm Bleek, Matthew Bunn, Ashton Carter, Charles Curtis, Harold Feiveson, Laura Holgate, Steven Kelman, Alexander Keyssar, William Potter, Frank von Hippel, three anonymous reviewers, and the numerous other current and former government, international organization, and nongovernmental organization officials who generously shared their time and expertise.