Nearly twenty years have passed since al-Qaeda terrorists carried out the attacks of September 11, 2001.1 During that interval, the United States has built a counterterrorism bureaucracy to manage, resource, and operationalize the nation’s intelligence, law enforcement, and military response to the threat posed by al-Qaeda in particular and terrorism more broadly. This counterterrorism enterprise has been remarkably successful from a tactical perspective, foiling attacks and disrupting terrorist networks. But it has been less successful from a strategic vantage point, given that more people today are radicalized to violent extremism than in 2001, representing a more diversified and globally dispersed terrorist threat.
