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United States President Barack Obama, left, speaks during a closing session with David Cameron, U.K. prime minister, center, and Dalia Grybauskaite, Lithuania's president, at the Nuclear Security Summit in Washington, D.C., U.S., on Friday, April 1, 2016. After a spate of terrorist attacks from Europe to Africa, Obama is rallying international support during the summit for an effort to keep Islamic State and similar groups from obtaining nuclear material and other weapons of mass destruction. Seated behind them are US Secretary of State John Kerry and US Secretary of Energy Ernest Moniz.<br />
Credit: Andrew Harrer / Pool via CNP/MediaPunch