The National Committee’s Track II dialogue on U.S.-China Strategic Security Dialogue (at times called the Northeast Asia Strategic Security Dialogue) began in 1999 and stemmed from an earlier National Committee mil/mil program (see Military-Military Programs) and the joint Stanford-Harvard Preventive Defense Project (PDP), a research collaboration of Stanford University and Harvard University's Kennedy School of Government set up by former Secretary of Defense William Perry and Assistant Secretary Ash Carter. "Preventive defense" is a concept for American defense strategy in the post-Cold War era, premised on the belief that the absence of an imminent, major, traditional military threat to American security presents today's leaders with an unaccustomed challenge and opportunity to prevent future Cold War-scale threats to international security from emerging. Up until then, PDP had focused on forging productive security partnerships with Russia and its neighbors, but wanted to engage an emerging China. The partnership with the National Committee, now in its fifteenth year, has provided opportunities for sustained personal interaction with military and political leaders in mainland China and Taiwan. The non-governmental, off-the-record, Track II dialogue explores opportunities for innovative thinking, airing of views, and the discovery of areas of possible cooperation. This ongoing collaborative project has resulted in over a dozen separate programs, held alternately in China and the United States but all focused on various aspects of Northeast Asian security issues and now extended to other areas of the world. The most recent meeting in this series was held at the Annenberg Retreat at Sunnylands, where Presidents Xi and Obama held their historic summit in June, 2013. This was the first group focused on Sino-American relations to gather there since then and participants felt a special responsibility to build on that meeting, as well as on the solid relationships built during fifteen years of prior NCUSCR-PDP dialogues. Four major areas were covered: bilateral relations (including mil/mil issues), North Korea and other Northeast Asia security issues, the situation after the U.S. withdrawal from Afghanistan and the resulting geopolitical strategy in Central Asia, and the challenges and opportunities in building a new major country relationship.