Silver Lining? The Effects of Epidemics on Terrorist Groups

In this study we examine the effects of epidemics on terrorist groups’ attack capacities. We consider two theoretical relationships between epidemics and terrorist groups. By weakening government counterterrorism defenses and increasing popular grievances, epidemics can provide a strategic environment that is conducive to terrorist groups, enhancing their capacity to commit more attacks, yield higher casualties and launch more logistically complex attacks. Conversely, epidemics can impair the abilities of terrorist groups to launch attacks by eroding group capacity and access to resources while incentivizing the state to increase its surveillance and policing capabilities. We test these two competing arguments using a database of over 620 terrorist groups for the period of 1970 to 2016. Our findings support the second argument. Terrorist groups based or operating in countries experiencing more and more intense epidemics commit fewer attacks, generally produce fewer casualties, commit a lower ratio of transnational to domestic attacks and less frequently use multi-mode attacks. We conclude with a discussion of the implications of these findings.