ISIS can draw on a “large cadre of Western fighters” that could attack in the U.S. and the terror threat posed by the group remains as dangerous as ever despite efforts to crush it militarily, the director of the CIA said Thursday.

“Unfortunately, despite all our progress against ISIL on the battlefield and in the financial realm, our efforts have not reduced the group’s terrorism capability and global reach,” CIA Director John Brennan testified to Congress using another acronym for the group.

“The resources needed for terrorism are very modest, and the group would have to suffer even heavier losses of territory, manpower and money for its terrorist capacity to decline significantly,” Brennan added. “In fact, as the pressure mounts on ISIL, we judge that it will intensify its global terror campaign to maintain its dominance of the global terrorism agenda.”

Brennan warned that the group already is preparing more attacks, including by infiltrating refugees into western nations.