Fly is senior fellow and director of the Future of Geopolitics and Asia programs and co-director of the Alliance for Securing Democracy at The German Marshall Fund of the United States. Fly served as counselor for Foreign and National Security Affairs to Senator Marco Rubio from 2013–2017, serving as his foreign policy advisor during his presidential campaign. Prior to joining Sen. Rubio’s staff in 2013, he served as the executive director of the Foreign Policy Initiative (FPI) from its founding in early 2009. Prior to joining FPI, Fly served in the Bush administration at the National Security Council (2008–2009) focusing on the Iranian nuclear program, Syria, missile defense, chemical weapons, proliferation finance, and other counterproliferation issues. Prior to that, he served in the Office of the Secretary of Defense (2005–2008 where he helped to develop U.S. strategy related to the proliferation of missiles as well as nuclear, chemical, and biological weapons.