International Studies Quarterly (2018) 0,1–10 International Military Interventions and Transnational Terrorist Backlash RESEARCH NOTE J AMES A. PIAZZA Pennsylvania State University AND S EUNG-WHAN C HOI University of Illinois at Chicago Are states that engage in foreign military interventions vulnerable to subsequent transnational terrorist attacks? If so, do all types of foreign interventions stimulate terrorism? Using data on international military interventions for 125 to 182 countries during the period from 1970 to 2005, we demonstrate that states experience more terrorism after they engage in military interventions. In particular, politico-strategic use of military force abroad—for example, interference in another country’s domestic disputes, territorial interventions, or interventions to affect local politics and policy—leads to increased subsequent transnational terrorist attacks for the intervener. In contrast, socioeconomic foreign military interventions, such as those geared toward providing humanitarian relief, protecting social groups, or securing economic interests, do not lead to an increase in transnational terrorist attacks against intervening states. Anecdotal evidence points to a positive and significant rela- wounded forty-five. Russian intelligence officials believe that tionship between foreign interventions and terrorist attacks this latest attack was “backlash” produced by Russian bomb- against the intervening state. Numerous observers point to ings of ISIS positions in Syria (Pinchuk 2017). US military interventions in the Middle East as an important The concern that foreign military interventions trigger motivator for anti-American terrorism, including the 1993 backlash in the form of increased risk of transnational ter- attack against the World Trade Centers and the September rorist attacks receives widespread attention in policy and 11, 2001, terrorist attacks by Al Qaeda. Indeed, Osama Bin nonacademic circles (see, for example, Norton-Taylor 2003; Laden cited the legacy of US military operations in Muslim Durani 2014; Zakaria 2015). It has become even more press- countries as a justification for the use of terrorism against ing as the United States has increased aerial drone attacks US targets (see Lawrence 2005, 17, 25). The 2004 and 2005 in places like Pakistan and Yemen (see, for example, Abbas suicide bombings of public transport systems in Madrid and 2013; Cronin 2013, 44–47; Pilkington and MacAskill 2015). London were launched, according to the perpetrators, in International military interventions and their attendant col- retaliation against Spanish and British participation in the lateral damage, the argument goes, provoke strong feelings 2003 US-led invasion and occupation of Iraq. The Decem- of resentment, both among the people experiencing the in- ber 2016 assassination of the Russian ambassador to Turkey tervention and sympathetic observers. These resentments was, the assailant proclaimed, in response to Russian air motivate direct and indirect support for nonstate militant strikes against the Islamic State (ISIS) in Syria.1 Most re- organizations that “strike back” at the intervening country cently, on April 3, 2017, a suicide bomber—suspected to through terrorist attacks. be a Chechen rebel who returned from Syria after having The 2006 US National Intelligence Estimate, prepared fought alongside the Islamic State—launched an attack on for then President George W. Bush, who was considering a St. Petersburg metro carriage that killed eleven people and further foreign military interventions after its 2003 invasion and occupation of Iraq, describes just this dynamic. The re- port, summarizing the conclusion of several US national in- James A. Piazza, PhD, is a liberal arts professor in the Department of Politi- cal Science at the Pennsylvania State University. His research focuses on terror- telligence agencies, argued that the invasion of Iraq had pro- ism and counterterrorism, and his published work has appeared in the American duced a strong negative backlash against the United States Journal of Political Science, Journal of Politics, International Studies Quarterly, Journal of in the wider Muslim World that caused radical Islamist ter- Conflict Resolution, Journal of Peace Science, Comparative Political Studies,andTerrorism rorist organizations to more effectively operate and recruit and Political Violence. new members worldwide (Office of the Director of National Seung-Whan Choi, PhD, is a professor in the Department of Political Science Intelligence 2006). at the University of Illinois at Chicago. His work has been published in journals including the American Journal of Political Science, British Journal of Political Science, Some scholarly work provides indirect evidence for the International Studies Quarterly, Journal of Conflict Resolution,andOxford Economic Pa- backlash phenomenon (for recent studies, see Azam and pers. He is the author of three books: Civil-Military Dynamics, Democracy, and Inter- Thelen 2010, 250–56; Choi and Piazza 2017, 284–91; Savun national Conflict, New Explorations into International Relations,andEmerging Security and Phillips 2009, 895–961). In this study, we delve fur- Challenges. 1 ther into the effects of international military interventions After fatally shooting Andrei Karlov, the Russian ambassador to Turkey, the on subsequent transnational terrorist attacks suffered by assailant, Mevlüt Mert Altınta¸s, shouted, “God is Great! Do not forget Aleppo, do not forget Syria!” (Arango and Gladstone 2016). the intervening country. We argue that not all military Piazza, James A., and Seung-Whan Choi. (2018) International Military Interventions and Transnational Terrorist Backlash. International Studies Quarterly, doi: 10.1093/isq/sqy026 © The Author(s) (2018). Published by Oxford University Press on behalf of the International Studies Association. All rights reserved. For permissions, please e-mail: [email protected] Downloaded from https://academic.oup.com/isq/advance-article-abstract/doi/10.1093/isq/sqy026/5063844 by Libraries of the ClaremontColleges user on 07 August 2018 2 International Military Interventions and Transnational Terrorist Backlash interventions prompt backlash from transnational terrorists. ars note that interventions are undertaken by states with We maintain that the type of intervention affects the likeli- high capacities to project conventional military force inter- hood of subsequent attacks against the intervener. Guided nationally and are frequently stronger than nonstate mili- by work conducted by Kisangani and Pickering (2007, 281– tants they oppose. Therefore, interventions produce an en- 83), we differentiate military interventions motivated by and vironment of conventional power asymmetry between the oriented around politico-strategic—“high politics”—from intervener and nonstate opponents. Given that terrorism is socioeconomic—“low politics”—objectives. We expect that a tactic of the conventionally weak (Crenshaw 1981, 387; politico-strategic use of military force increases subsequent Kydd and Walter 2006, 50), it would not be surprising to see transnational terrorist attacks, but that socioeconomic inter- an increase in terrorist attacks against interveners as mili- ventions do not. tants turn to terrorism to compensate for their conventional In our study we produce results that are consistent with weakness (see Condra et al. 2010,7;Pettinger 2015, 2–3).2 these theoretical predictions. Statistical analysis on interna- Our study seeks to address two gaps within the litera- tional military interventions for 125 to 182 countries during ture on the impact of interventions on transnational ter- the period from 1970 to 2005 provides evidence that inter- rorism. First, with the exceptions of Braithwaite (2015) who national military interventions geared toward providing hu- examines military “footprints” within a country, a concept manitarian relief, protecting social groups, or for economic akin to occupation—and Neumayer and Plümper (2011) motivations do not result in more transnational terrorism. who test the impact of provision of US military aid on ter- However, interventions undertaken for political or strategic rorist attacks against Americans—existing studies neglect reasons result in higher levels of subsequent transnational to test whether international military interventions trigger terrorist attacks for the intervener. In the next sections we transnational terrorism backlash. They only measure the outline the relevant literature, present and test our theoret- impact of interventions on terrorist attacks perpetrated by ical argument, and then briefly conclude with the implica- nationals of the country experiencing the intervention. In tions of the findings. contrast, our study provides a direct test of the backlash con- cept by investigating the impact of a country’s engagement in a military intervention overseas on its subsequent experi- Literature Review ence of terrorism. We also recognize that terrorist backlash Our study fits within a wider quantitative literature on may not only come from citizens of the country experienc- the effects of international interventions and foreign oc- ing the intervention, but also may be perpetrated by citizens cupations on terrorist activity. A large body of work shows of other countries that are outraged and are sympathetic to that terrorist activity increases in countries experiencing the “victims” of such interventions. foreign military occupations or foreign military interven-