1. AAAS Science & Technology Policy Fellow, Center for Technology and National Security Policy, National Defense University, Fort Lesley J. McNair, Washington, DC 20319, USA
2. These views are those of the authors and not the official views of the National Defense University, the U.S. Defense Department, or the U.S. Government.
3. Science & Technology Fellow, Foreign Policy Studies Program, The Brookings Institution, 1775 Massachusetts Avenue, NW, Washington, DC 20036, USA