In April 2009, President Obama announced an international initiative to secure all vulnerable nuclear materials worldwide within 4 years. Nonproliferation programs administered by the National Nuclear Security Administration (NNSA) are working to secure nuclear materials in Russia and other countries. GAO assessed (1) U.S. governmentwide efforts to implement the President's 4-year nuclear material security initiative; (2) the status and challenges, if any, of NNSA's nuclear security programs in Russia; and (3) NNSA efforts to secure nuclear materials in countries other than Russia. To address these issues, GAO analyzed U.S. nuclear security strategies and plans and interviewed U.S. and Russian government officials. This report summarizes the findings of GAO's classified report on securing nuclear materials worldwide. GAO suggests that Congress consider extending the deadline for NNSA to complete Material Protection, Control, and Accounting (MPC&A) program activities in Russia. GAO recommends that the Department of Energy (DOE) and NNSA take several actions regarding three nonproliferation program efforts in Russia, such as clarifying the remaining scope and costs of MPC&A work in Russia. GAO also recommends that the National Security Council (NSC) lead interagency development of a more detailed implementation plan for the President's 4-year initiative. DOE and NNSA agreed with the recommendations. NSC did not comment on GAO's recommendations.