Read more from Slate's Sept. 11 anniversary coverage.
The ultimate in such thinking—common during the administration of George W. Bush and continued more sporadically in the administration of his successor, Barack Obama—is to characterize the terrorist threat as "existential." In 2008, Homeland Security Secretary Michael Chertoff even proclaimed the "struggle" against terrorism to be a "significant existential" one—carefully differentiating it, apparently, from all those insignificant existential struggles Americans have waged in the past. Rather amazingly, such extreme expressions, which if accepted as valid can close off all judicious evaluation of the problem, have only rarely been called into question.
In stark contrast, Glenn Carle, a 23‑year veteran of the Central Intelligence Agency, where he was deputy national intelligence officer for transnational threats, has warned, "We must not take fright at the specter our leaders have exaggerated. In fact, we must see jihadists for the small, lethal, disjointed and miserable opponents that they are." Al-Qaeda "has only a handful of individuals capable of planning, organizing and leading a terrorist organization," and although they have threatened attacks, "its capabilities are far inferior to its desires."
As for the domestic situation, the FBI and other investigative agencies have been unable to uncover a single true al‑Qaeda sleeper cell anywhere in the United States. Indeed, they have been scarcely able to unearth anyone who might even be deemed to have a "connection" to the diabolical group.
Assessing the threat from homegrown Islamist terrorists, Brian Jenkins stresses that their number is "tiny," representing one out of every 30,000 Muslims in the United States. This "very low level" of recruitment finds very little support in the Muslim community at large: "they are not Mao's guerrillas swimming in a friendly sea." Given this situation, concludes Jenkins, what is to be anticipated is "tiny conspiracies, lone gunmen, one-off attacks rather than sustained terrorist campaigns." In the meantime, note other researchers, Muslim extremists have been responsible for 1/50th of 1 percent of the homicides committed in the United States since 9/11.
Because terrorism of a considerably destructive nature can be perpetrated by a very small number of people, or even by a single individual, the fact that terrorists are few in number does not mean there is no problem, and from time to time some of these people may actually manage to do some harm, though in most cases their capacities and schemes—or alleged schemes—seem to be far less dangerous than initial press reports suggest.
The situation seems scarcely different in Europe and other Western locations. Political scientist Michael Kenney has interviewed dozens of officials and intelligence agents and analyzed court documents. He finds that, in sharp contrast with the boilerplate characterizations favored by the DHS, Islamic militants there are operationally unsophisticated, short on know‑how, prone to make mistakes, poor at planning, and limited in their capacity to learn.
Indeed, since 9/11 no terrorist entity within the United States has been able to detonate even a simple bomb. And, except for the London Underground bombings of 2005, neither has any in the United Kingdom.
One can also focus on the kind of terrorism that really concerns people in the developed world by tallying the violence committed by Muslim extremists outside of war zones, whether that violence is perpetrated by domestic Islamist terrorists or by ones with international connections. Three publications from think tanks have independently provided lists or tallies of such violence committed in the several years after the 9/11 attacks. The lists include not only attacks by al‑Qaeda but also those by its imitators, enthusiasts, look‑alikes, and wannabes, as well as ones by groups with no apparent connection to it whatever.
Although these tallies make for grim reading, the total number of people killed in the years after 9/11 by Muslim extremists outside of war zones comes to some 200 to 300 per year. That, of course, is 200 to 300 too many, but it hardly suggests that the destructive capacities of the terrorists are monumental. For comparison, during the same period more people—320 per year—drowned in bathtubs in the United States alone. Or there is another, rather unpleasant comparison. Increased delays and added costs at U.S. airports due to new security procedures provide incentive for many short‑haul passengers to drive to their destination rather than flying, and, since driving is far riskier than air travel, the extra automobile traffic generated has been estimated in one study to result in 500 or more extra road fatalities per year.
The fact that the public has difficulties with probabilities when emotions are involved does not relieve those in charge of the requirement, even the duty, to make decisions about the expenditures of vast quantities of public monies in a responsible manner. In the end, one might darkly suspect, various versions of probability neglect are grasped because, if realistic probabilities that a given target would be struck by terrorists were multiplied into the risk calculation and if the costs of protection from unlikely threats were sensibly calculated following standard procedures, it would be found that vast amounts of money have been misspent.
Tomorrow: We'd have to foil 1,667 Times Square-style attacks every year to justify current spending on homeland security.