The U.S. intelligence community says terrorists are trying to change the way they communicate because of what they learned from Edward Snowden’s admitted leaks of classified information about government surveillance programs.

“We can confirm we are seeing indications that several terrorist groups are in fact attempting to change their communications behaviors based specifically on what they are reading about our surveillance programs in the media,” a U.S. intelligence official told CNN.

He emphasized these are terrorist groups operating outside the United States and are not limited to al Qaeda affiliates.

Intelligence has been gathered on both Sunni and Shia groups, he said, noting the risk to national security is that the groups “go dark” in terms of the U.S. ability to listen to them and watch them until it can “reacquire them” through new means.

As for whether that poses an immediate threat to national security, “I am not telling you people are dying, I am telling you terrorists are already trying to change their behavior,” he said.