Security conditions at U.S. military bases were raised overnight because of potential threats of a jihadist attack.

The official move from U.S. Northern Command comes hours after FBI Director James Comey said there are thousands of ISIS followers in the United States.

“We have a general concern, obviously, that ISIL is focusing on the uniformed military and law enforcement,” Comey told reporters Thursday.  “It’s like the devil sitting on their shoulders, saying ‘kill, kill, kill.”

“We have the same concern about the potential threat posed by violent homegrown extremists,” said Captain Jeff Davis, spokesman for the U.S. Northern Command which oversees all U.S. military installations in the continental U.S.

CNN reported that an official confirmed “Force Protection Bravo” status, defined as an “increased and predictable threat of terrorism.”  The last time military bases in the homeland had this condition for any significant length of time was the tenth anniversary of the 9/11 attacks.

“We are doing this as a prudent measure due to a lot of things in the news lately,” Davis said. “While this change is not tied to a specific credible threat, recent events have led us to recognize the need to take prudent steps to ensure that our security measures can be increased quickly.”

FBI director Comey said the biggest problem is that these people “go dark” like Elton Simpson, one of the two terrorists who attempted the Texas Mohammed Cartoon contest attack.

“The haystack is the entire country,” Comey said. “We are looking for the needles, but increasingly the needles are unavailable to us. … This is the ‘going dark’ problem in living color. There are Elton Simpsons out there that I have not found and I cannot see.”