Following 9/11, Americans’ fears of terrorists-especially domestically based Islamic extremists-reached near-hysteria levels. The government and media reports stoked fears that malign actors living in the US had not only the desire but the means to wreak extreme havoc and destruction. Early reports estimated slightly more than 300 al Qaeda operatives living in the United States, and it wasn’t long before this number became 2,000 or 5,000 domestic terrorists. As these estimates snowballed, so did spending on federal counterterrorism organizations and measures, and it now totals over one trillion dollars. The federal government launched more covert operations in the name of fighting terrorist adversaries than they did in the entirety of the forty-five year Cold War. The scale of these efforts has been enormous, yet somehow Americans remain fearful of what they perceive to be a massive terrorist threat. But how well-founded is this fear? Is the threat of terrorism in the United States as vast as it seems and are counterterrorism efforts effective and appropriately-scaled?

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