The head of the FBI says the agency remains focused on the potential domestic threat posed by Islamic State militants.

FBI Director James Comey spoke Monday at a counterterrorism conference in Manhattan.

Comey says it’s “extremely difficult” to try to identify every American who travels to Syria in response to recruitment efforts by the Islamic State group.

The director also says there’s a persistent threat from online propaganda by Islamic State and other terror groups that encourages would-be terrorists to kill without leaving home.

(AP)