The most significant achievement to emerge from the 2014 Nuclear Security Summit was a pledge by 35 countries to observe the terms of a joint agreement, known as Strengthening Nuclear Security Implementation. Promoted strongly by the chairs of all three nuclear summits—the United States, South Korea, and the Netherlands— the 2014 initiative is an important step towards creating a robust global security system designed to prevent nuclear materials from falling into the hands of terrorists. Yet China, along with Russia, India, and Pakistan, did not join the pledge. Beijing has not offered any explanations. China not only can join the new initiative, it should join it—because joining is in China’s own national interest.