Has the Global War on Terror Changed the Terrorist Threat? A Time-Series Intervention Analysis

Abstract

Whether the Global War on Terror (GWOT) has changed the terrorist threat is a matter of controversy. This study, using transnational terrorism events data from 1993 through 2004, employs a time-series approach to investigate the extent to which the onset of the GWOT (beginning with the invasion of Afghanistan) and related events (the invasion of Iraq, the capture of Saddam Hussein, and the release of photos from Abu Ghraib) are associated with changes in transnational terrorist activity, its frequency, dispersion, lethality, type of attack, and type of victim of transnational terrorist incidents.

Replication data and results discussed in the text are available from the author. The theory and evidence presented in this article are developed at greater length in the author's book, The War on Terror and the Transformation of Terrorist Activity (Cambria Press, 2008). The author is Visiting Professor at the Institute for Conflict Analysis and Resolution at George Mason University.

Notes

1. See Arreguin-Toft (2001). See also Pape (2003), who argues that strategy has been key in the success of suicide terrorism, which he tallies has been effective in about 50 percent of the cases in which it has been used. He notes that it was effective in compelling American and French military forces to leave Lebanon in 1983, Israeli forces to abandon Lebanon in 1985, and Israeli forces to quit the Gaza Strip and West Bank in 1994 and 1995. He also suggests that it was effective in getting the Sri Lankan government to create an independent Tamil state from 1990 on and the Turkish government to grant autonomy to Kurds in the late 1990s. See also Dershowitz (2002).

2. The term “preemption” has been defined as striking an enemy as it prepares to strike. However, some observers have suggested that the Bush administration has expanded the definition to include “prevention,” that is, striking an enemy even in the absence of specific evidence of an imminent attack. See O’Hanlon, Rice, and Steinberg (2002).

3. According to a 2002 United Nations report, Al Qaeda recruitment picked up in 30 to 40 countries during the period the United States began building up for the Iraq invasion (see Lynch 2002). According to a CSIS report, interviews of foreign fighters in Iraq indicated that images of abuse at Abu Ghraib were an important catalyst in their decision to fight (see Obaid and Cordesman 2005).

4. The International Terrorism: Attributes of International Events (ITERATE), which is available in a text as well as numeric format, provides a rich events data set of more than 13,000 incidents of transnational terrorism across 192 countries (as well as international organizations such as the UN) from 1968 through 2004. ITERATE data through 1978 is available through the Inter-University Consortium for Political and Social Research (ICPSR) at Ann Arbor Michigan. The data from 1979 through 2004 are proprietary and available for purchase from Edward Mickolus at Vinyard Software in Dunn Loring, VA.

5. The RAND-MIPT Terrorism Incident Database (1968–2008) is an extension of the RAND Chronology of International Terrorism. Until March 2008 it was available on the Web from the Oklahoma City National Memorial Institute for the Prevention of Terrorism at http://www.tkb.org./Home.jsp. The database, which includes approximately 10,000 incidents of international/transnational terrorism for the period from 1968–2004, was originally developed as an “uncoded textual chronology” of significant international terrorist incidents. It is currently being merged with the Global Terrorism Database (GTD) managed by the National Consortium for the Study of Terrorism and Responses to Terrorism (START) at the University of Maryland. Among RAND terrorism analysts who have contributed to the RAND Chronology over time are such terrorism experts as Brian Jenkins, Bruce Hoffman, and more recently Michael Wermuth and Kim Cragin.

6. Previous published quantitative analyses of transnational terrorism have been limited almost exclusively to one proprietary database (ITERATE, Mickolus et al. 2004). The current author's own analysis of several years of ITERATE, however, indicates that it misses many items that fit its own definition of transnational terrorism and are covered in the text-based RAND-MIPT database originally compiled by terrorism experts Brian Jenkins and Bruce Hoffman. To make up for this shortfall, the author supplemented the ITERATE data set with RAND-MIPT data (which was coded following the ITERATE format). To the author's knowledge, no one has used the RAND data set for quantitative analyses because, while it has been publicly available on the Web, it has only been available in text format and coding is time consuming. Other databases also exist. In particular, the U.S. State Department compiles an annual series of transnational terrorist events. However, this data set is limited because definitions of what qualifies as international terrorism are influenced by U.S. policy preferences at a given time. For further discussion of this problem, see Falkenrath (2001).