Support for this research was provided by the Department of Homeland Security (DHS) through the National Consortium for the Study of Terrorism and Responses to Terrorism (START) Grant N00140510629. Any opinions, findings, and conclusions or recommendations in this document are those of the authors and do not necessarily reflect views of DHS. An earlier version of this paper was presented at the American Association for the Advancement of Science meetings, Boston, MA, 2008. We would like to thank Erin Miller for assistance with the database and several anonymous reviewers for helpful comments on an earlier draft.
Trajectories of terrorism
Attack patterns of foreign groups that have targeted the United States, 1970–2004
Version of Record online: 25 SEP 2009
© 2009 by the American Society of Criminology
Criminology & Public Policy
Special Issue: SPECIAL ISSUE: Homeland Security and Terrorism
Volume 8, Issue 3, pages 445–473, August 2009
How to Cite
LaFree, G., Yang, S.-M. and Crenshaw, M. (2009), Trajectories of terrorism. Criminology & Public Policy, 8: 445–473. doi: 10.1111/j.1745-9133.2009.00570.x
- Issue online: 25 SEP 2009
- Version of Record online: 25 SEP 2009
- global terrorism database;
- terrorism targets;
- terrorism trends;
- terrorist groups;
- anti-U.S. attacks;
- trajectory analysis;
- terrorism waves
Although researchers began to assemble open-source terrorism event databases in the late 1960s, until recently most of these databases excluded domestic attacks. This exclusion is particularly misleading for the United States because, although the United States is often perceived to be the central target of transnational terrorism, the domestic attacks of foreign groups targeting the United States are often ignored. We began this article with 53 foreign terrorist groups that have been identified by U.S. State Department and other government sources as posing a special threat to the United States. Using newly available data from the Global Terrorism Database composed of both domestic and transnational terrorist attacks, we examined 16,916 attacks attributed to these groups between 1970 and 2004. We found that just 3% of attacks by these designated anti-U.S. groups were actually directed at the United States. Moreover, 99% of attacks targeting the United States did not occur on U.S. soil but were aimed at U.S. targets in other countries (e.g., embassies or multilateral corporations). We also found that more than 90% of the non-U.S. attacks were domestic (i.e., nationals from one country attacking targets of the same nationality in the same country). We used group-based trajectory analysis to examine the different developmental trajectories of U.S. target and non-U.S. target terrorist strikes and concluded that four trajectories best capture attack patterns for both. These trajectories outline three terrorist waves—which occurred in the 1970s, 1980s, and the early 21st century—as well as a trajectory that does not exhibit wave-like characteristics but instead is characterized by irregular and infrequent attacks.
Our results underscore the importance of proximity for terrorist targeting. Terrorists, like ordinary criminals, are likely to choose targets close to their operational base. However, when attacks occur further from the terrorists' home bases, they are more deadly. Approximately half of the terrorist organizations studied here exhibited wave-like boom and bust attack trajectories. Given that most attacks by groups identified as threats by the U.S. government are in fact aimed at non-U.S. domestic targets, the United States should pursue efforts to strengthen the capacity of local governments to combat terrorism and to communicate to them our understanding that groups that are anti-United States are also a threat to local governments. In framing counterterrorism policies, the United States should put threats into perspective by acknowledging that we are the exception and local governments are the rule. Terrorism is not just about us.