The Plots that Failed: Intelligence Lessons Learned from Unsuccessful Terrorist Attacks Against the United States

While much of the focus of terrorism research is on successful terrorist attacks, the most significant lessons for terrorism prevention may come from examination of terrorist plots and attacks that do not succeed. This article analyzes 176 terrorist plots against American targets that have been thwarted or otherwise failed during the past 25 years. It considers what kinds of intelligence and security measures are most useful in counterterrorism, and argues that the conventional wisdom about why intelligence fails-because analysts and agencies are unable to "connect the dots"-is wrong. Most plots, especially domestic terrorist plots, are not foiled through imaginative analysis, but through conventional law enforcement efforts and aggressive domestic intelligence collection that reveal to authorities just what the plotters are up to.