https://www.cnbc.com/2017/09/24/obama-personally-warned-mark-zuckerberg-about-fake-news-on-facebook.html

Former president Barack Obama personally warned Facebook founder and CEO Mark Zuckerberg in a post-2016 election meeting to check the spread of fake news on the site, but he was told there was no easy fix, according to Washington Post report on Sunday.

The Nov. 19 meeting reportedly took place in Lima, Peru, at a gathering of world leaders two months before Donald Trump's inauguration. The meeting followed Zuckerberg saying that the idea fake news driven by Russian-linked operatives on the site could have an major impact on voting was "crazy."