In an April 2009 speech in Prague, President Obama pledged that his Administration would launch "a new international effort to secure all vulnerable nuclear material around the world within four years." To motivate world leaders to achieve this goal, the President hosted a Nuclear Security Summit in Washington, DC, on April 12-13, 2010. Leaders of 47 countries attended the summit, including many heads of state. Attendees represent a wide geographic range of states and nuclear capabilities, and include China, India, Israel, and Pakistan. The summit resulted in a joint statement saying that international cooperative action is necessary to prevent an act of nuclear terrorism. Summit attendees also pledged to improve nuclear security standards, bring international agreements into force, and share best practices. Nuclear security measures refer to a wide range of actions to prevent theft or diversion of nuclear material or sabotage at an installation or in transit. They could include physical protection measures, material control and accounting, personnel reliability screening, and training. A broader understanding of nuclear security also includes measures to prevent and detect illicit trafficking-- cargo inspections, border security, and interdiction measures. The U.S. government has worked for more than a decade both domestically and in partnership with other countries to address this problem through multiple programs at the Departments of Defense, Energy, Homeland Security, and State. The International Atomic Energy Agency has also played a lead role in these efforts, particularly since the 9/11 terrorist attacks. Congress will continue to decide on funding for the U.S. domestic and international programs focused on nuclear material security and nuclear terrorism prevention. Congress is also likely to assess implementation of the Administration's goal to secure nuclear materials by the end of 2013. The Obama Administration's FY2011 and FY2012 congressional budget request proposed overall increases in funding for nuclear security-related accounts, with the stated purpose of ramping up programs to meet the President's four-year goal.