UPDATED: Aaron Sorkin, who won a screenwriting Oscar for “The Social Network,” a fictionalized retelling of the early rise of Mark Zuckerberg and , has weighed in on the debate over the social giant’s policy to accept all political advertising regardless of whether it’s factual or not.

Sorkin’s message to Zuck: You’re wrong.

In an op-ed published Thursday in the New York Times, Sorkin expressed in an open letter to Zuckerberg admiration for the Facebook CEO’s “deep belief in free speech,” which is the justification Zuckerberg has provided for the hands-off policy on political advertising. But, Sorkin said, the Facebook decision to keep running ads for political campaigns is spreading outright lies — which have a “dangerous effect on our elections.”

“[T]his can’t possibly be the outcome you and I want, to have crazy lies pumped into the water supply that corrupt the most important decisions we make together,” Sorkin wrote. “Lies that have a very real and incredibly dangerous effect on our elections and our lives and our children’s lives.”

Facebook’s service is currently running an ad, bought on behalf of Donald Trump’s 2020 presidential campaign, claiming that former VP Joe Biden gave the Ukrainian attorney general a $1 billion bribe to not investigate his son. “Every square inch of that is a lie and it’s under your logo,” Sorkin wrote in the op-ed. “That’s not defending free speech, Mark, that’s assaulting truth.”

Zuckerberg responded in a Facebook post by quoting from Sorkin’s script for 1995’s “The American President,” delivered in the film by Michael Douglas, who plays the titular president:

“America isn’t easy. America is advanced citizenship… You want to claim this land as the land of the free? Then the symbol of your country can’t just be a flag; the symbol also has to be one of its citizens exercising his right to burn that flag in protest. Show me that, defend that, celebrate that in your classrooms. Then, you can stand up and sing about the land of the free.”

Zuckerberg, on Facebook’s quarterly earnings call Wednesday, admitted the political advertising policy was controversial even as he tried to downplay the business impact — claiming ads from political campaigns represent less than 0.5% of revenue. “This may lead to more investigations, and the candidates may criticize us,” he said. The 2020 election year is shaping up to be “a very tough year” for the company, Zuckerberg added.

Those comments, and Facebook’s report of blockbuster Q3 financial results, came just minutes after Twitter CEO Jack Dorsey announced that his company would ban all political advertising effective Nov. 22. “This isn’t about free expression,” Dorsey tweeted. “This is about paying for reach.” Dorsey took a swipe at Facebook’s position, saying, “it‘s not credible for us to say: ‘We’re working hard to stop people from gaming our systems to spread misleading info, buuut if someone pays us to target and force people to see their political ad…well…they can say whatever they want!’”

In his op-ed, Sorkin recounted Zuckerberg’s “public accusation that the movie was a lie” but the screenwriter said he didn’t contest that because the screenplay for “The Social Network” was “vetted to within an inch of its life by a team of studio lawyers with one client and one goal: Don’t get sued by Mark Zuckerberg.”

Sorkin also recalled Facebook COO Sheryl Sandberg was invited to a preview screening of “The Social Network” and in the middle of the film turned to the producers in the room to ask, “How can you do this to a kid?” Zuckerberg was 26 at the time of the 2010 film’s release.

Regarding Facebook’s ad policies, Sorkin wrote, “I hope your COO walks into your office, leans in (as she suggested we do in her best selling book), and says, ‘How can we do this to tens of millions of kids?'”

Zuckerberg has faced criticism from politicians including Biden, Sen. Elizabeth Warren and Hillary Clinton but so far has repeatedly defended his stance for Facebook to not fact-check political ads. During a tense congressional hearing last week about Facebook’s Libra cryptocurrency plans, Zuckerberg was asked about the political ad policy and said, “in most cases, in a democracy, I believe people should be able to see for themselves what politicians they may or may not vote for are saying and judge their character for themselves.”