FBI Director James Comey said the Khorasan Group, an al Qaeda affiliate in Syria, may still be working on a plan to hit the United States.

"Khorasan was working and may still be working on an effort to attack the United States or our allies, and looking to do it very, very soon," he said on CBS's "60 Minutes."

"I can't sit here and tell you whether it's their plan is tomorrow or three weeks or three months from now," he said.

"Given our visibility, we know they're serious people, bent on destruction. And so we have to act as if it's coming tomorrow."