9/11 Commission vice chair: 'We did not keep our finger on ISIS all the way'

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The former vice chairman of the 9/11 Commission said Wednesday that terror group ISIS "snuck up" on the U.S. amid "enormous turmoil" across the Middle East.

"You have an intelligence community and the United States with enormous capabilities, very highly professional. But they can't focus on everything all the time,” Lee Hamilton said on Fox News’ “American Newsroom.” “It's undoubtedly the fact that ISIS kind of snuck up on us in a way and became a much more powerful actor in that region of the world than we had previously thought."

He added that it was an enormous task for intelligence officials to monitor every possible threat but added, “we did not keep our finger on ISIS all the way.”

Hamilton said it was “hard to judge” in hindsight if giving support to the Free Syrian Army would have helped prevent the spread of the Islamic State there.

"It's just a very complex matter," he said. "It's an easy thing to say, 'Well, if we armed the rebels, we could have solved this problem or been much further down the road in solving it.' That's by no means clear that that's the case."

Hamilton said the most “genuine threat” to the country now involves the jihadist training of European and U.S. citizens abroad because of the terrorists' ability to easily reenter the country.

"Many of them have passports," he said. "They do not require a visa to come into the United States."

While Hamilton has "no doubt" that the U.S. is in a better position to track down terrorists than 10-15 years ago, he warned that there is still a "long way to go" to eradicate the threat.

"We must not become complacent," he said. "It's a threat. It's a dangerous threat."