In 2011, he served as executive director of the U.S. Advisory Commission on Public Diplomacy. Previously, Armstrong was an adjunct professor of public diplomacy at the Annenberg School of Journalism and Communication at the University of Southern California. In 2010, he founded and served as President of the MountainRunner Institute and published a blog on public diplomacy and strategic communication. He is a member of the Board of Directors of the Public Diplomacy Council, a member of the International Institute of Strategic Studies and the National Press Club. Armstrong earned a B.A. and an M.P.D. from the University of Southern California.
Armstrong serves as the chair of the Special Committee on the Future of Shortwave Broadcasting and is a member of the Advisory Committee and the Special Committee on the Creation of a Chief Executive Officer.
He was confirmed as member of the Broadcasting Board of Governors on August 1, 2013.