The truly frightening thing about the shooting that killed five military members on Amnicola Highway last week: It could happen again, and it's hard to stop.
"If it can happen in Chattanooga, it can happen anywhere, anytime, anyplace," U.S. Rep. Michael McCaul, chairman of the U.S. House Committee on Homeland Security, said Sunday.
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McCaul, a Texas Republican, said on ABC's "This Week" that the FBI is doing forensic examinations of shooter Mohammad Youssef Abdulazeez's cellphone, computer and trips to Jordan to determine if he was involved with ISIS, also known as ISIL or the Islamic State.
Abdulazeez shot to death four U.S. Marines and a Navy petty officer in a shooting spree that lasted nearly a half hour Thursday at the U.S. Naval and Marine Reserve Center on Amnicola Highway. The 24-year-old Hixson resident had reportedly traveled to the Middle East in recent years.
McCaul said this is the kind of case federal officials were most worried about — the one that slips through the cracks.
"What keeps us up at night are the ones we don't know about," he said. "And I'm afraid this case falls into that category."
It may be more frightening to the public if Abdulazeez was a lone wolf, rather than working for a terror organization, Tennessee Gov. Bill Haslam said Sunday on "Meet the Press."
If Abdulazeez was working for ISIS, it might be easier to comprehend that someone else was pulling the strings that set the shooter in motion, Haslam said. But if he really was on his own, then it's harder to understand and more difficult to investigate his motive.
"And it makes it really hard, obviously, to think, 'How do we protect ourselves against that in the future?'" the governor said.
McCaul didn't say whether his office believes Abdulazeez was directly involved or influenced by ISIS, but he stressed that the terror organization is a threat to America today.
One of the biggest challenges security officials face in keeping tabs on ISIS is the sheer volume of activity. Homeland Security has to keep track of more than 200,000 ISIS tweets per day, McCaul said.
"The chatter is so loud, and the volume is so high, that it's a problem that's hard to stop," he said.
Terrorism experts have said ISIS is adept at using social media to spread influence, gain sympathizers and recruit them.
McCaul said ISIS members from Syria "activate people in the United States" to attack Americans, targeting military installations and police officers.
"We have the threat over the Internet, which is a new threat that's out there, McCaul said. "A new generation of terrorists."
Just eight days before the Chattanooga attacks, FBI Director James Comey told Congress that the ISIS social media campaign poses an enormous threat.
"It buzzes in their pocket so there is a device, almost a devil on their shoulder, all day long that says, 'Kill, kill, kill,'" he told lawmakers.
He also said although the FBI has thwarted some attacks, "I cannot see me stopping these indefinitely."
McCaul said Homeland Security has "rolled up" 60 cases of ISIS followers in America in the last year.
McCaul pointed out that Homeland Security blocked a potential attack over the Fourth of July, and said he thinks the fight needs to go overseas. He wants to find the people who are sending these tweets, he said.
Contact staff writer Evan Hoopfer at firstname.lastname@example.org or 423-757-6731.