Whether the reasons are economic, psychological, or social—or some combination thereof—terrorism has been an entrenched part of human activity since ancient times. Homicidal zealotry did not begin with the first-century Jewish Zealots, who violently sought to overthrow the Roman rule they thought was such an affront to God. Deadly assassinations did not originate with the Assassins, a Muslim faction in the Middle Ages who were known for the fearless dagger attacks they perpetrated on their enemies. Murderous terrorism did not begin in the French Revolution's Reign of Terror, when radicals resorted to a liberal use of the guillotine in supposed service of “liberty, equality, and fraternity.”

Although well-rooted in the past, modern terrorism is clearly distinctive because of its international presence and catastrophic potential. Of course, it is this destructive character that has had such a marked influence on recent trends in risk management. The regular occurrence of major international events since September 11, 2001—including the New Delhi Parliament attacks (2001); the Madrid train bombings (2004); the London subway bombings (2005); and the attacks in Mumbai (2008)—demonstrate why it is safe to assume that this new breed of terrorism will be a central part of the risk management process for some years to come.

Challenges to Assessing Exposure Levels