Jon Wolfsthal is director of the Nuclear Crisis Group, a Global Zero initiative to prevent the use of nuclear weapons. From 2014 to 2017, he served as special assistant to former U.S. President Barack Obama and as senior director for arms control and nonproliferation at the National Security Council. In that post, he was the most senior White House official, setting and implementing U.S. government policy on all aspects of arms control, nonproliferation, and nuclear policy. Prior to that, he served as the deputy director of the James Martin Center for Nonproliferation Studies at the Monterey Institute for International Studies. From 2009 to 2012, he served as the special adviser to then U.S. Vice President Joe Biden for nuclear security and nonproliferation and as director for nonproliferation on the National Security Council. He supported the Obama administration’s negotiation and ratification of the New START arms reduction agreement with the Russian Federation, and helped support the development of nuclear policy, including through the 2010 Nuclear Posture Review.