A little under a year ago, Facebook CEO Mark Zuckerberg dismissed as pretty crazy the idea that a disinformation campaign could have used his site to influence the outcome of the election.

With regulators now breathing down his neck for exactly that reason, Zuck might wish he could take those words back.

On Tuesday, Facebook general counsel Colin Stretch, along with his counterparts at Twitter and Google , testified before the Senate Judiciary Subcommittee on Crime and Terrorism, where he disclosed that Facebook facilitated the spread of Russian-backed content to an estimated 126 million Americans during the 2016 election.

That figure is based on Facebook data indicating that 120 Russian-backed Facebook pages published 80,000 posts between January 2015 through August 2017 (with an influence campaign potentially stretching back as early as 2014 ). Those posts were in turn seen directly by 29 million Americans, who, by interacting with them, distributed the falsities throughout their own personal networks.

That means more than half of all eligible voters in 2016 saw deliberately misleading political content pushed by a foreign adversary on Facebook.