When Terrorism and Counterterrorism Clash: Preemptive Force and Its Impact on Yransnational Terrorism. A Time Series Intervention Analysis

Problem . The impact of the Global War on Terrorism (GWOT), with its emphasis on preemptive military force, is a matter of considerable debate. This dissertation uses a time series intervention approach to evaluate 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.

Methods . After merging transnational terrorism incident data from ITERATE and RAND-MIPT for 1993-2004, I extracted quarterly time series of the frequency, dispersion, lethality, type of attack and type of victim of transnational terrorist incidents. I then used a time series intervention approach (with ARIMA modeling) to test the impact of the GWOT and the other events on the subsequent pattern of transnational terrorist activity.

Results . The onset of the GWOT and the release of photos from Abu Ghraib were both associated with significant upward shifts in the frequency and lethality of transnational terrorist incidents. Similar effects were found for the invasion of Iraq when incidents in Israel were excluded. While the onset of the GWOT was associated with an increase in dispersion (number of countries with incidents), the capture of Saddam Hussein had the opposite effect. Both the invasion of Iraq and the release of photos from Abu Ghraib were followed by rises in incidents in Muslim countries. Although hostage takings declined after the onset of the GWOT, they increased significantly after Abu Ghraib. Escalating incidents with multinational victims were significantly associated with the onset of the GWOT and the invasion of Iraq while incidents claimed by or known to be perpetrated by "Islamist groups" were significantly increased only after Abu Ghraib.

Significance . While force may be used by governments to preempt future transnational terrorist attacks, the results suggest that at least in the near term it increases such activity, makes it deadlier and/or shifts the tactics or targets. These results appear to be even more likely when force disintegrates into "barbarism" as it did at Abu Ghraib. Conversely, the capture of a significant leader may have a mitigating effect. These findings have implications for policy and conflict theory.