Author Biography

James L. Regens is Regents Professor and Director, University of Oklahoma Center for Intelligence and National Security. He holds the Edward E. & Helen T. Bartlett Foundation Chair at the University of Oklahoma Health Sciences Center. Dr. Regens has demonstrated expertise in modeling/simulation, risk assessment, statistical/spatial analysis techniques, and decision analysis. He has field experience in Western Europe, Russia, China, the Middle East, Latin America, and sub-Saharan Africa. Dr. Regens has authored and co-authored over 200 publications including articles in Proceedings of the National Academy of Sciences and eight books. He has been PI for almost $40 million in research funding, primarily to conduct a series of large-scale, interdisciplinary research projects. Dr. Regens is a member of the Council on Foreign Relations, the International Institute for Strategic Studies, the Association of Former Intelligence Officers, and the International Association for Intelligence Education, and a Fellow, Royal Society for Public Health.

Nicholas A. Mould is a Fellow in the University of Oklahoma Center for Intelligence and National Security. Dr. Mould is an Instructor in the School of Electrical and Computer Engineering at the University of Oklahoma. His research interests include signal, image and video processing, computer vision, stochastic signal processing and math and science education. Dr. Mould has published articles in a variety of journals including Signal, Image and Video Processing; Infrared Physics & Technology; Journal of Policing, Intelligence and Counter Terrorism; and Journal of Intelligence Analysis. He is a member of the Institute of Electrical and Electronics Engineers (IEEE) and the International Association for Intelligence Education.



Subject Area Keywords

Radicalization, Terrorism / counterterrorism, Violent extremism


In this article we estimate the influence of leadership changes on the operational dynamics associated with terrorist attacks conducted by the Islamic State and its predecessors. Because the focus of our research is empirical, the study uses data for 2,131 successful attacks between October 2002 and December 2014 to examine differentials in operational tempo, attack severity, primary tactics employed, and principal targets. The data are aggregated on a monthly basis to estimate the probabilities associated with specific attack sequences in terms of the following primary tactics: (1) firearms, (2) explosives, (3) hostage-taking/kidnapping, and (4) attacks involving combinations of (1), (2), and/or (3). The analysis is placed in a broad historical and strategic context in order to explore two key issues: (1) The effect of leadership change on terrorist group activity and (2) The implications for counterterrorism and counterinsurgency efforts. Our analysis reveals a myriad of conceptual, theoretical, and policy implications.


The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


This research was supported by the Defense Intelligence Agency, Grant # HHM402-14-1-007 (PI: Regens). The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of DIA or the US government.