The nature of terrorism has changed in Robert Mueller’s dozen years as FBI director, but his concerns for the future are much the same as when terrorists struck on Sept. 11, 2001, merely a week after he’d taken over the bureau.

As he wraps up his FBI tenure, Mueller (MULL-er) worries that terrorists will once again target planes or finally pull off an attack using a weapon of mass destruction.

Mueller sees terrorism as a shifting landscape, evolving from Osama bin Laden’s global brand in the aftermath of the Sept. 11 attacks to the splintering threats arising in the fallout from the Arab Spring across the Middle East. Mueller says newly emerging cadres of violent extremists will present threats down the road.

Mueller spoke to reporters at FBI headquarters.

(AP)