Scott Sagan, Stanford University; Li Bin, Tsinghua University; Harald Mueller, Peace Research Institute Frankfurt; Hugh Powell, Foreign and Commonwealth Office, United Kingdom; Bruno Tertrais, Fondation pour la Recherche Strategique. This session was part of the 2007 Carnegie International Nonproliferation Conference, “Tomorrow's Solutions,” June 25–26, in Washington, D.C., which addressed the critical challenges confronting the nonproliferation regime and offered policy recommendations to stop the spread and use of nuclear weapons and materials.