Harlem Suarez grabbed a jalapeno pepper from his plate and took a big bite. The heavily tattooed Cuban-American crepe-maker was eating dinner with two new friends, Shariff and Mohammed, at a Denny’s in Key West on a warm June night. Suarez wanted to impress them but they laughed instead, joking in Arabic that he seemed suicidal.

Civil liberties advocates have criticized the FBI for targeting vulnerable people susceptible to manipulation because of mental illness or intellectual disabilities. They say that individuals who lack the resources or faculties to carry out devastating attacks on their own are getting caught up in labyrinthine government fictions. According to a Human Rights Watch study of 27 post-9/11 terror investigations, at least eight defendants showed signs that they were struggling with serious psychological issues or intellectual impairment. The counterargument is that terror recruiters look for people with those very traits. Violent jihadists need not be master tacticians or Merlins with improvised explosives to pose a public safety threat, according to Ali Soufan, a former FBI agent and author of “The Black Banners: The Inside Story of 9/11 and the War Against al Qaeda.””Many terrorists are literally idiots,” Soufan wrote in a Wall Street Journal book review of “The Terror Factory,” by Trevor Aaronson. “But that doesn’t mean that they aren’t dangerous, and if al Qaeda gets their hands on them, they will utilize them …”