Tech CEOs testify about online child sexual exploitation at US Senate hearing - live updates

We are now back from a break, and we are now hearing questions from Senator Alex Padilla.

Let's quickly examine why this hearing has covered several topics in addition to child safety - including China, fentanyl and antisemitism.

Lawmakers on Capitol Hill don't get much time to address Big Tech executives and hold them to account.

Today has been a good example of what it is like on those rare occasions it does happen.

While this hearing is ostensibly focused on the issue of child sexual exploitation online, senators have grilled the witnesses on various related topics including data privacy content moderation, the Chinese government and even China's treatment of Ughyurs.

And, as they often do, they have rattled off difficult questions and demanded the witnesses answer in brief, preferably saying yes or no.

But the five witnesses - particularly Mark Zuckerberg and Shou Zi Chew, both of whom have endured this kind of grilling before - have attempted to respond with careful answers that have satisfied nobody.