A former CIA officer said Thursday he has no doubt Islamic State (ISIS) sleeper cells are already planted on U.S. soil.
An unnamed U.S. intelligence official told CNN there's already an indication of ISIS sleeper cells in Europe that could target U.S. embassies and other American interests.
But former CIA officer Bob Baer told the network ISIS is already on this side of the Atlantic.
"I have been told with no uncertainty there are ISIS sleeper cells in this country," he said.
Though CNN said two U.S. officials had refuted the claim, they're worried ISIS militants with passports might travel to the United States to launch attacks on American soil, CNN reported.
One ISIS fighter already has hinted as much.