Why would an all-American kid become a jihadist?

So why would a nice all-American kid become a jihadist?

This disturbing and topical question courses through “United States of Jihad: Investigating America’s Homegrown Terrorists” by Peter Bergen. At first blush, Bergen appears an unlikely candidate to survey such fraught and decidedly psychological terrain. A national security analyst for CNN and author of several books in the field, including “Manhunt: The Ten-Year Search for Bin Laden From 9/11 to Abbottabad,” Bergen has gravitated toward the study of operational strategies — those employed by terrorist outfits as well as the agencies pursuing them. Even here, he sometimes cannot help enmeshing his narrative in discussions of terrorist and counterterrorist means and methods. Yet he never loses sight of his primary subjects, “typical Americans and typical American jihadists,” such as the San Bernardino attackers. The result is an engrossing and edifying book.

Over the course of 11 chapters, the author takes readers into the lives of individuals who perpetrated atrocities such as the Fort Hood massacre and the Boston Marathon bombings, as well as those who left the United States to join jihadist groups in places such as Syria and Somalia. All in all, Bergen examined the cases of 330 terrorists and would-be terrorists, many inspired by Al Qaeda or Islamic State, in preparation for “United States of Jihad.” He repeatedly came across what intelligence analysts Mitchell Silber and Arvin Bhatt have called a “cognitive opening” — often some precipitating event or personal crisis — that eventually leads to the adoption of extremist views. The author also endorses the findings of psychiatrist Marc Sageman, who “concluded that ‘social bonds’ formed by friendships played a more important role than ideology in creating jihadist groups.”

This point bears emphasizing. The mere existence of admittedly incendiary passages in the Koran and Hadith cannot in and of itself explain why some Muslims and not others are drawn to such material. However, when a troubled, resentful, and self-reinforcing group casting about for a belief system finally settles on one, members may well view it in reductive terms. According to Bergen, something like this happened with the Boston Marathon bombers, Tamerlan and Dzhokhar Tsarnaev. “For both brothers,” he argues, “the combination of Binladenist propaganda such as [English-language jihadist magazine] Inspire, anti-American resentments, and the absence of moderating influences was enough to flatten their conception of Islam into a justification for lethal vengeance.”

Exaggerating the significance of the threat you’re tasked with assessing is an all-too-common feature of national security studies, with the Cold War offering almost comical examples. It is to Bergen’s immense credit that, without downplaying the threat of Islamist terrorism — home-grown or directed at America by groups abroad — he refrains from overstating it and attempts to maintain perspective. You are “five thousand times more likely to be killed by a fellow citizen armed with a gun than by a terrorist inspired by the ideology of Osama bin Laden,” he stresses.

With some justification, Bergen criticizes the FBI’s practice of instigating terrorist plots among Islamists who might otherwise have never crossed that line. After all, it isn’t every ideological extremist who progresses to acts of violence. The author prefers weaning people off radical Islam or (better yet) arresting their drift toward it, as opposed to entrapment. For such remonstrative efforts to succeed, Bergen maintains that the participation of moderate Muslim clerics is imperative.

That’s a reasonable but hardly original argument. Nevertheless, the author deserves kudos for simultaneously recognizing the potential of secular Muslims — who are too often ignored — to change people’s attitudes. Secular Muslims are particularly well-positioned to allay ordinary Americans’ sometimes indiscriminate suspicion of Islam’s adherents, as well as provide their (numerically few) alienated coreligionists with a model that might woo them away from holy war and martyrdom.

Bergen, however, neglects to mention one other way to rein in folks who’re trotting merrily toward jihadism. It’s a tactic recommended in a study conducted by the British think tank Demos: biting satire. Think you’d like to lasso any wannabe Tsarnaev brothers out there as they strut down jihad lane in between primping for selfies and polishing their Twitter argot? If so, keep this in mind: It’s too bad, but snarky ridicule will probably prove a lot more effective than high-minded moralizing.

UNITED STATES OF JIHAD:

Investigating America’s Homegrown Terrorists

By Peter Bergen.

Crown, 387 pp., illustrated, $28.