Former Obama CIA chief: It's guaranteed that a Sydney-style terror attack will happen in the U.S. soon

“What concerns me the most is we’re going see this kind of terrorism around the world and we’re going to see it here,” Morrell said.

“We need to be prepared for that. You know, it shouldn’t surprise people when this happens here sometime over the next year or so, guaranteed.”

Morrell also said he was not surprised that a crisis like this broke out in Australia, which has witnessed more than 300 of its citizens traveling to fight in Iraq and Syria, 70 of whom are fighting for IS (ISIS or ISIL).