His research and teaching focuses on the causes, consequences, and amelioration of nuclear, biological, and chemical weapons proliferation to states and non-state actors. During 2012-13, he was on leave from those positions to serve as Senior Advisor to the Assistant Secretary of Defense for Nuclear, Chemical and Biological Defense Programs under a Council on Foreign Relations International Affairs Fellowship in Nuclear Security, where one of his responsibilities was participating in chemical and biological terrorism red and blue-team exercises.