Mark Zuckerberg on Monday hit back at Sen. Elizabeth Warren over her accusations that Facebook allowed President Trump to run ads on the social network that contained false claims.

In an attempt to pressure Zuckerberg over the issue, Warren last week bought ads on Facebook with deliberately false information.

“Breaking news,” the ad read, “ Mark Zuckerberg and Facebook just endorsed Donald Trump for re-election.”

Zuckerberg addressed Warren’s complaints in a conference call with journalists where he outlined Facebook’s plan to protect against foreign interference heading into the 2020 presidential election.

Asked about taking down ads that contain information that is obviously false, Zuckerberg said that it is not Facebook’s decision to determine what information gets to voters.

“I just think that in a democracy people should be able to see for themselves what politicians are saying, and I think that people should make up their own minds about which candidates are credible and which candidates have the kind of character that they want to see in their elected official,” the 35-year-old billionaire said.

Warren, a leading Democratic candidate for 2020, has also recently accused Zuckerberg of helping Trump win the presidency in 2016 — and of turning a blind eye to underhanded tactics that could help the president win reelection next year.

“Facebook is actively helping Trump spread lies and misinformation,” Warren said, calling the social network “unprepared” for next year’s election and adding that Zuckerberg has learned “little” from 2016.

Zuckerberg on Monday appeared determined to show Facebook is taking election security seriously by outlining a series of new initiatives to protect against foreign meddling in the 2020 election, including more clearly marking accounts controlled by state-owned media.

“This is one of my top priorities for the company,” Zuckerberg said in the conference call with reporters. “Elections have changed significantly, and Facebook has changed, too.”

Zuckerberg said the company will also be cracking down on any attempts to suppress voting through ads, including banning ads that “suggest voting is useless or advise people not to vote” or that misrepresent polling dates or locations.

Zuckerberg said Facebook refuses to eliminate political ads entirely not for financial reasons but because the “controversy isn’t worth the very small portion of our business they make up.”

“Banning political ads would favor incumbents and whoever the media has decided to cover the most,” Zuckerberg said. “And I don’t think that’s what we’re trying to do here.”