What is the most serious danger facing the world today?
Barack Obama, George W. Bush, Mohamed ElBaradei, and Dick Cheney all give the same answer: nuclear terrorism. If terrorists succeed in exploding a nuclear weapon in New York, Boston, or London, the other issues we care about will not matter much.
In 2009, President Obama proposed an ambitious agenda to address this danger. Among the steps he called for was a Global Summit on Nuclear Security. Seven years and four summits later, including the final one this spring in Washington, we can take stock of progress—and the Belfer Center’s role in helping conceive and sustain it. Policy impact is rarely a simple case of cause and effect.