Encryption came up during Tuesday's hearing on content moderation — highlighting the wide range of topics lawmakers have covered over the past four hours.
Sen. Joni Ernst asked Mark Zuckerberg how the company's plans to add end-to-end encryption to its Messenger platform would impact its ability to crack down on illegal content, such as images of child sexual abuse. Such encryption would prevent both the company and law enforcement from accessing private messages between users.
"The reason why we're moving to encryption is because people want greater privacy and security in their messaging systems," Zuckerberg said.
The Facebook CEO acknowledged that the company would need to "find and develop some new tactics" to identify problematic content despite encryption, such as looking at patterns of activity or relying on individual users to flag such content for review.
"We've grown increasingly sophisticated at that," he added. "Overall I would say that this is something we are very focused on, and I agree with your concern."