In 2009, President Barack Obama announced from Prague’s Hradcany square that “the most immediate and extreme threat to global security” was nuclear weapons in the hands of terrorists, and world leaders listened. A year later, 47 of these leaders responded to Obama’s call “to secure all vulnerable nuclear material around the world within four years” when they gathered in Washington, DC, for the first Nuclear Security Summit. Since then, nearly 400 kilograms of highly enriched uranium (HEU) have been removed from 10 countries. And both Russia and the United States have worked hard on HEU destruction efforts—48 metric tons and 7 metric tons, respectively. In March, 50 nations are taking part in the Seoul Nuclear Security Summit. But how can these countries ensure that the momentum toward a global nuclear security culture isn’t lost, and the Seoul summit does not devolve into just another gathering? Three authors explore this question: from the United States, Sharon Squassoni (2012); from Turkey, Mustafa Kibaroglu (2012); and from India, Rajiv Nayan. The authors are nuclear security experts and members of the Fissile Materials Working Group, which publishes a monthly column at www.thebulletin.org.