So far, none have been brought to trial and the lack of progress in capturing Khattala has frustrated U.S. intelligence officials and lawmakers who want to see him and the others prosecuted. One official said that Khattala continues to operate in eastern Libya with impunity.

“He’s as free as a bird,” the official said.

In an interview, Rep. Mike Rogers (R-Mich.), who chairs the House intelligence committee, said the United States was not making a strong enough effort to capture Khattala.

“I don’t believe we have adequately resourced or operationally planned to remove Khattala or those involved in the Libyan 9/11 attacks,” Rogers said. “There are consequences for our lack of pursuit. . . . You have removed the notion of certainty in deterrence and you cannot lose that.”