The U.S. National Academies (NAS) and the Russian Academy of Sciences (RAS), building on a foundation of years of interacademy cooperation, conducted a joint project to identify U.S. and Russian views on what the international nuclear security environment will be in 2015, what challenges may arise from that environment, and what options the U.S. and Russia have in partnering to address those challenges. The project's discussions were developed and expanded upon during a two-day public workshop held at the International Atomic Energy Agency in November 2007. A key aspect of that partnership may be cooperation in third countries where both the U.S. and Russia can draw on their experiences over the last decade of non-proliferation cooperation. More broadly, the following issues analyzed over the course of this RAS-NAS project included: safety and security culture, materials protection, control and accounting (MPC&A) best practices, sustainability, nuclear forensics, public-private partnerships, and the expansion of nuclear energy.