Rep. McCaul: 'Dark' Communications Big Terror Challenge

The ability of terrorists to "go dark" and communicate over the Internet or by other means without being detected is one of the biggest challenges the West faces, says House Homeland Security Committee Chairman Mike McCaul.

"If you can't see what they're saying very difficult to stop it," the Texas Republican said Sunday on CBS's "Face the Nation."

"We know they're talking from Morocco to people in Paris and Belgium, but also in United States," McCaul said. "We've caught communications where they talk to people in New York and in D.C. and, quite frankly, everywhere."

McCaul said the Paris attackers undoubtedly used dark communications to relay their terror plan that left 130 people dead and more than 350 injured.

He said outreach into Muslim communities in the United States must continue to identify the signs of radicalization.

"Just like the Boston bomber who got kicked out of his mosque for being too radical," he said. "We didn't know about that; it would have been nice to have known."

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