President Trump fired the first shot, tweeting:
Zuckerberg fired back with a Facebook post that read, in part, "Trump says Facebook is against him. Liberals say we helped Trump. Both sides are upset about ideas and content they don't like. That's what running a platform for all ideas looks like."
Research Fellow at the Hoover Institution at Stanford Bill Whalen said he's surprised Zuckerberg took the bait.
"It's the old joke about you don't wrestle with a pig in the mud," Whalen said. "Why? Because the pig enjoys it and you end up getting dirty."
He believes President Trump picked the fight to distract from other things that haven't gone his way this week, for example -- another failed attempt to repeal and replace Obamacare.
Whalen also believes Facebook is struggling with its identity, and Zuckerberg needs to better explain to people what Facebook is going to be about moving forward. He said it's no longer just a social network.