- Rep. Devin Nunes said the United States is struggling to track ISIS
- "We don't know what we don't know," the House Intelligence chairman said Sunday
"We just don't know what we don't know," Rep. Devin Nunes, R-California, told CNN's Jake Tapper Sunday on "State of the Union."
"There's nothing specific, except for the threat that they've been putting out there on the Internet," Nunes said. "So at this point, we have to take everything seriously."
Nunes defended a House-passed bill that would halt U.S. acceptance of refugees from Iraq and Syria until law enforcement officials take new steps to vet those refugees.
And he urged President Barack Obama's administration to take a broader approach to ISIS -- stretching from North Africa to Afghanistan and Pakistan, and with allies in Europe, where he said the group appears to have a "command and control structure."
Nunes said the United States was aware of some of the terrorists involved in the Paris attacks -- but they were just a few of the many people intelligence officials are attempting to monitor.
"We did have many of these people identified, but there are so many thousands and thousands of them, and they're all over Western Europe and even in the United States, and then with the technology they're using today and the rules and the lessons that they've learned through fighting us the last 15 years, they've gotten very good at hiding from intelligence services across the globe," he said.