Since the beginning of this year, ISIL has published more than 1,700 messages online, including videos and online magazines, he said. Some social media providers take quick action to shut down ISIL recruiters, but others do not, he added.
"There is still much work to be done to encourage greater vigilance and broader sense of corporate responsibility to address this threat to public safety," Mulligan said.
Neither Mulligan nor Steinbach named the companies they were most concerned about, although McCaul mentioned anonymous messaging apps Kik and Whatsapp as well as "data-destroying" apps Surespot and Wickr.
Most lawmakers didn't question Steinbach's call for a rewrite of CALEA, although Representative Will Hurd, a Texas Republican and former CIA officer, said the proposed changes would have implications for privacy.
"I'm a little bit nervous when we start talking about CALEA expansion," Hurd said.
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