"It's really people that can get self-radicalized by looking at information on the internet and, then, having access to materials and supplies that are commercially available here -- effect an attack on the system," Pekoske said. He noted that the perpetrators of two recent attacks in New York, a truck ramming in October and a subway bombing in December, "weren't people that were on anybody's scope at that point in time."
He went on to add that the TSA still focuses "on the organized terrorist groups as well. So we really need to keep our eye on both, make sure that our security systems keep both in mind."
The TSA continues to rely on so-called "behavior detection" -- identifying visual and verbal cues indicative of ill intent -- to spot self-radicalized would-be terrorists, as well as members of organized terror organizations who warrant a second look from TSA.
However, Pekoske also said participation by the public, like adhering to the U.S. Department of Homeland Security's "if you see something, say something" campaigns, is key in warding off self-radicalized individuals before they attack. It's why the TSA has tweaked its motto from "not on my watch" to "not on our watch."