In recent decades, the United States has led international efforts to halt the proliferation of weapons of mass destruction. But many of President Trump’s statements on nuclear weapons suggest a coming shift in US policy. Could America’s new posture spark a renewed nuclear arms race? With Ivo H. Daalder, President, Chicago Council on Global Affairs; Robert L. Gallucci, Distinguished Professor in the Practice of Diplomacy, Walsh School of Foreign Service, Georgetown University; Scott Sagan, Senior Fellow, Freeman Spogli Institute for International Studies, Stanford University. Moderated by Rachel Bronson, Executive Director and Publisher, Bulletin of the Atomic Scientists.