Looming over Facebook’s decision to limit the story’s spread was a warning the FBI gave the company about dumps of Russian propaganda on the eve of the election, Zuckerberg explained in an interview with podcast host Joe Rogan released Thursday.

“The background here is the FBI basically came to us, some folks on our team, and was like, ‘Hey, just so you know, you should be on high alert … we thought there was a lot of Russian propaganda in the 2016 election. We have it on notice that basically, there’s about to be some kind of dump that’s similar to that. So just be vigilant,'” Zuckerberg said.