In February 1998, Osama bin Ladin and Ayman al Zawahiri published a signed statement declaring a fatwa against the United States. Bin Laden, al Zawahiri, and the other signatories of the statement called for retribution against the United States because it had “declared war against God.” The statement went on to claim that it was the individual duty of every Muslim to murder any American anywhere on earth. Three months later, in an interview on ABC-TV, bin Laden stated: “We believe that the worst thieves in the world today and the worst terrorists are the Americans. Nothing could stop you except perhaps retaliation in kind. We do not have to differentiate between military and civilian.” As we now know, the fatwa resulted in the unprecedented 9/11 attack against the United States.

As we discuss in subsequent chapters, the tragedy of 9/11 was a defining moment for the United States, other Western nations, and the Islamic nations in many profound ways. Chapter 10 focuses on the economic costs of terrorism, including the direct and indirect costs of 9/11. Chapter 11 evaluates homeland security, and Chapter 12 speculates on the future of terrorism. In this chapter, we report the results of several studies that quantify the ways in which the type, location, and nature of terrorist incidents have changed since the fatwa and in the aftermath of 9/11. We also discuss how 9/11 affected our collective psyche and how it has made us feel more aware of and more vulnerable to terrorism.