In Terrorism before and after 9/11 – a more dangerous world? , researchers from the US Department of Defense and the RAND Corporation used data from the University of Maryland's Global Terrorism Database and the Uppsala Conflict Data Program to produce a quantitative look at the long-term trends in terrorism: the short upshot is, terrorism is up globally because of massive increases in places where US troops have been sent as occupiers, presenting a target-rich environment for terrorists -- but when you take those places out of the data, terrorism is way, way down worldwide.
What are we to make of these empirical patterns and what are the policy implications?
First, it is possible that post-9/11 counterterrorism efforts have contributed to reducing incidents of non-insurgency terror. In the aftermath of 9/11, the United States and other countries became more diligent in undertaking preventive measures against terrorists, frustrating their plans and degrading their organizations. The data indicate that such labors may have paid dividends in the form of fewer attacks outside of conflict zones, though we are unable to conclusively say this. Moreover, we do not have information on the extent to which counterterrorism efforts have foiled terror plots, which could mean these measures are having an even greater effect than the data show.
Additionally, large deployments of U.S. soldiers in Iraq and Afghanistan also likely provided a richer target environment for jihadists. Those who wanted to kill crusaders could attempt to do so without having to plan and execute much more difficult external operations. This is one of several possible ways in which Western intervention in conflict zones may be linked to higher numbers of terror incidents in those areas.
Second, it is important to point out that the decline in terrorism we describe could be reversed in the next several years. For instance, as foreign fighters return from current warzones such as Iraq and Syria to their countries of origin, attacks may start taking place elsewhere. Foreign fighters may leverage the training and experience they garnered in combat zones to carry out future attacks in their home countries. They may also gain access to Western states and inspire other attackers.
Third, and most importantly, the evidence raises difficult questions about the efficacy of the U.S. approach to the war on terror in the future. Is the United States willing to maintain a sustained presence in Afghanistan, the Middle East, and parts of Africa to confront a problem that is increasingly regional and local? If so, what type of commitment should it maintain and for how long?
Terrorism Before and During the War on Terror: A Look at the Numbers [Sean Zeigler and Meagan Smith/War on the Rocks]