Comey targeted recent moves by Apple and Google to encrypt user data on their devices, saying that while much of the data is backed up to the cloud — and thus accessible by law enforcement with a search warrant — other data is not, creating a “black hole for law enforcement.”

“Both companies are run by good people, responding to what they perceive is a market demand,” he said. “But the place they are leading us is one we shouldn’t go to without careful thought and debate as a country.”