Jasen J. Castillo is an associate professor and Evelyn and Ed F. Kruse '49 Faculty Fellow in the Bush School of Government and Public Service at Texas A&M University. Prior to joining the Bush School, Jasen worked in the Department of Defense's Policy Planning Office. Before working in the Office of the Secretary of Defense, he was an analyst at the RAND Corporation, where his research focused on military strategy, nuclear deterrence, and WMD terrorism. Prior to RAND, he was a consultant for the Institute for Defense Analyses. Dr. Castillo earned his Ph.D. in political science from the University of Chicago, where he received research support from the National Science Foundation and the Smith Richardson Foundation. His research interests include US defense policy, military history and nuclear deterrence. His publications include: Endurance and War: The National Sources of Military Cohesion, (Palo Alto: Stanford University Press, 2014); Understanding Russian Nuclear Strategy and Assessing Escalation in Conventional Conflicts, PR-3039-OSD (Santa Monica, CA: RAND, October 2017); National Will to Fight: Why Some States Keep Fighting and Others Don’t, PR-3191-A (Santa Monica, CA: The Rand Corporation, October 2017); Will to Fight: Defining, Modeling, and Simulating the Will to Fight of Tactical and Operational Military Units, PR-3149-A (Santa Monica, CA: The Rand Corporation, October 2017); Flexible Response Revisited: Assessing Pakistan’s Potential Nuclear Strategies, PM-2383 (Santa Monica, CA: The Rand Corporation, October 2007); Striking First: Preemptive and Preventive Attack in U.S. National Security Policy, (Santa Monica, CA: The Rand Corporation, October 2004); “Nuclear Terrorism: Why Deterrence Still Matters,” Current History, Vol. 2, No. 668 (December 2003), Economic Growth and Military Expenditures, MR-112-A, (Santa Monica, CA: The Rand Corporation, October 2002). Currently, he is working on a book project exploring the military requirements of deterrence and U.S. nuclear weapons policy.