James A. Piazza’s research while affiliated with Pennsylvania State University and other places

Experts argue that the internet has provided expanded opportunities for violent extremist groups to propagandize and recruit. The Islamic State of Iraq and Syria, or ISIS, is an exemplar in that it has heavily invested in an online presence and uses online communities and social media to attract and retain supporters. Does ISIS’s online presence translate into a higher probability that individuals in its target audience will become supporters? In this study we analyze over 6,000 individuals in six Arab countries to find if those that use the internet to follow political news or to express political views are more likely to support ISIS. We find that respondents who get their news online are significantly more likely to support ISIS than those who follow the news on television or print media. Moreover, those who use online fora for political expression are also more likely to express support for ISIS. Indeed, individuals who engage in online political discussion are more likely to support ISIS than those who engage in conventional political activity, though less than those who engage in contentious political behaviors such as attending a political protest. We conclude with a brief discussion of the academic and policy implications of these findings.

What impact does engagement in crime have on terrorist group survival? In theory criminal activity may decrease group survival by damaging group legitimacy or prompting government crackdowns. Conversely, crime might boost group survival by facilitating access to revenues or by further taxing state policing capacity. Moreover, different types of crime might have different effects. We investigate the impact of crime on terrorist group survival using cross-sectional data on 578 terrorist groups observed between 1970 and 2007. We find that engagement in crime reduces a group’s chance of demise by around 50% and extends its lifespan by around 7 years on average. Terrorist groups involved in narcotics are less likely to end by police or military force, but are also less likely to win political concessions. We find that groups involved in extortion live the longest and are also less likely to end by force or by splintering.

Regime type has opposing effects on terrorism. If a regime constrains the executive branch, then terrorism may be more prevalent. If, however, a regime allows all viewpoints to be represented, then grievances may be held in check, resulting in less terrorism. Regimes that value constituents’ lives and property will also act to limit attacks. We formulate a game-theoretic model, containing a terrorist group and targeted government, that captures these opposing forces and supports a nonlinear relationship between regime type and terrorism. This model indicates how diverse samples in the literature can result in different relationships between regime type and terrorism. Seldom does it support the positive relationship that is prevalent in the terrorism literature. We apply a large variety of empirical techniques to show that regime type has a robust inverted U-shaped impact on various terrorism measures. Foreign policy variables (e.g., alliance with the United States) are not a robust influence on terrorism.

Do states with oil wealth experience more terrorism and, if so, why? Drawing from the intrastate war literature, this study considers several factors that prospectively mediate the relationship between oil wealth and terrorism: state weakness; rentier state authoritarianism; corruption of government officials; income inequality; human rights violations; foreign military intervention; and heightened separatist activity. Based on structural equation modeling on a sample of 130 non-OECD countries for the period 1970–2012, the paper produces two main empirical findings. First, while onshore oil production increases terrorist attacks in countries, on- and offshore production and oil revenues from exports do not increase such attacks. Second, the impact of oil on terrorism is mediated through increased human rights abuses. Exploitation of oil is found to be associated with a worsening of physical integrity rights abuses that, in turn, lead to popular grievances that help to fuel terrorist campaigns.

Counterterrorism strategies involving the killing of terrorists are a prominently used but controversial practice. Proponents argue that such strategies are useful tools for reducing terrorist activity, while critics question their effectiveness. This article provides empirical insight into this strategy by conducting a series of negative binomial regression and Tobit estimations of the impact of killing Provisional Irish Republican Army (PIRA) terrorists as well as members of the Catholic community on counts of PIRA bombings and targeting activity in Northern Ireland for the period 1970-1998. We consider the impact of discriminate and indiscriminate killings (where only PIRA militants are killed versus those in which both militants and civilians are also killed) on subsequent PIRA improvised explosive device (IED) attacks. Our findings illustrate that while total and discriminate counterterrorism killings have little to no effect on PIRA IED attacks, indiscriminate counterterrorism killings increased PIRA bombings overall and prompted the Provisional IRA to specifically target civilians in IED events. We conclude by discussing the scholarly and policy implications of these findings.

Qualitative studies of terrorist movements frequently highlight the importance of diaspora communities as important factors in producing and sustaining terrorist activity in countries. The underlying theoretical argument is that bifurcation of tight-knit minority communities between countries nurtures separatist or irredentist sentiments among affected community members, thus prompting terrorist activity, while minority community members in other countries might mobilize financial and political resources to support terrorist activity among their compatriots. In this study, we empirically test whether transnational dispersion, versus domestic concentration, of minority communities in countries produces higher incidents of terrorism. Conducting a series of negative binomial estimations on a reshaped database of around 170 countries from 1981 to 2006, derived from the Minorities at Risk database and the Global Terrorism Database, we determine that both transnational dispersion of kin minority communities and domestic concentration of minorities within countries increase terrorism and that transnational dispersion is a particularly robust predictor of terrorist attacks.

This study examines the effect of foreign military interventions on the incidence of suicide attacks. It presents three alternative theoretical explanations: foreign military interventions may boost insurgent use of suicide attacks (a) by fomenting a nationalist backlash that sanctions the use of more extreme and unconventional tactics like suicide attacks, (b) by providing more and better targets against which suicide attacks can be launched, or (c) by prompting insurgents to use suicide tactics in order to overcome their power asymmetries and to confront better defended targets that are enhanced by interventions. We test these competing explanations using a battery of statistical tests on cross-national, time-series data for 138 countries during the period from 1981 to 2005. We find that only foreign interventions with specific features – pro-government interventions involving larger numbers of ground troops – boost suicide attacks in countries experiencing interventions. This finding suggests that by tipping the balance of power against insurgents and hardening targets in the context of assisting a local government, foreign military interventions are likely to increase use of suicide attacks by regime challengers.

This study tests three categories of motivations for domestic right-wing terrorism in the USA: economic grievances, particularly those produced by economic restructuring; societal changes that challenge notions of white male privilege; and political and public policy elements that stoke resentments. Executing a series of negative binomial regression estimations on state-level data in the USA for the period 1970-2011, I find that measures of societal factors—specifically increase in abortion rates and growing female participation in the labor force—and political indicators such as Democratic Party control of the White House, precipitate right-wing terrorist attacks. Factors associated with economic hardships—such as poverty, the decline of manufacturing employment and the “Farm Crisis”—as well as growth of the non-white population, control of state government by the Democratic Party and growth of average Federal Income Tax rates—are not found to be significant predictors of right-wing terrorism.

While some scholars have theorized that repression reduces terrorism because it raises the costs of participating in terrorist activity by dissidents, others argue that repression stimulates terrorism by either closing off nonviolent avenues for expressing dissent or by provoking or sharpening grievances within a population. This study investigates these contradictory sets of expectations by considering whether or not different specific types of repression yield different effects on patterns of terrorism in 149 countries for the period 1981 to 2006. By assessing the impact of nine specific types of repression on domestic terrorism, the study produces some interesting findings: while, as expected, forms of repression that close off nonviolent avenues of dissent and boost group grievances increase the amount of domestic terrorism a country faces, types of repression that raise the costs of terrorist activity have no discernible suppressing effect on terrorism.

Why do members of some ethnic groups rebel against the state? One approach holds that groups subject to exclusion from national politics engage in armed conflict. We theorize that the presence of resource wealth moderates the effect of political exclusion. Ethnic groups subject to exclusion whose settlement area includes oil wealth are more likely to experience the onset of armed conflict than groups experiencing exclusion alone. We depart from the convention of cross-national analysis to examine subnational, geocoded units of analysis—ethnic group settlement areas—to better capture the impact of natural resource distribution. Using data on ethnic group political exclusion derived from the Ethnic Power Relations database and geo-coded indicators, we conduct a series of logistic regression analyses for the years 1946 to 2005. We find that exclusion alone increase the likelihood of conflict, while the presence of oil wealth further raises the risk of war.