Mark Zuckerberg defended the presence of Holocaust denial on Facebook in a lengthy and, at times, bizarre interview with Recode’s Kara Swisher on Tuesday. His position has been condemned by Jewish organizations who argue that Facebook is responsible for preventing hateful speech on its platform, and that allowing it causes harm.

The Facebook CEO said of Holocaust deniers—an example that he volunteered in order to demonstrate the platform’s complicated relationship with disinformation: “I don’t think that they’re intentionally getting it wrong… It’s hard to impugn intent and to understand the intent.”

Zuckerberg clarified that he is Jewish, and finds the rejection of the Holocaust’s events “deeply offensive.” But he ultimately believes that deniers are misinformed or mistaken.

Several hours after Recode published the interview, Zuckerberg emailed Swisher to elaborate:

I enjoyed our conversation yesterday, but there’s one thing I want to clear up. I personally find Holocaust denial deeply offensive, and I absolutely didn’t intend to defend the intent of people who deny that.

Our goal with fake news is not to prevent anyone from saying something untrue—but to stop fake news and misinformation spreading across our services. If something is spreading and is rated false by fact checkers, it would lose the vast majority of its distribution in News Feed. And of course if a post crossed line into advocating for violence or hate against a particular group, it would be removed. These issues are very challenging but I believe that often the best way to fight offensive bad speech is with good speech.

These comments are part of Facebook’s broader controversy around censorship, the limits of free speech, and bias. A series of reports and investigations this year illuminated Facebook’s role in spreading disinformation, interfering with elections, and destabilizing communities around the world.

And this week the company was scrutinized for its comments about InfoWars, a conspiracy theory-peddling website—its founder Alex Jones called the Sandy Hook mass shooting a “false flag” operation—which Facebook refuses to ban, preferring to demote individual posts and Pages.

“Holocaust denial is a willful, deliberate, and longstanding deception tactic by anti-Semites that is incontrovertibly hateful, hurtful, and threatening to Jews,” Anti-Defamation League (ADL) CEO and National Director Jonathan Greenblatt told Motherboard.

Last year Facebook and ADL, along with technology companies like Google and Twitter, partnered up to combat online hate. They established the Cyberhate Problem-Solving Lab, which seeks engineering solutions to remedy hate speech on the web.

At the time, Monika Bickert, Facebook’s head of global policy management, (who testified before the House Judiciary Committee this week on behalf of Facebook), said: “Building a global community that is safe and supportive means engineering new solutions to solve new problems. We work hard to create a safe environment on Facebook.”

In the Recode interview, Zuckerberg said that disinformation that incites harm (the example he gave was Myanmar’s Rohingya genocide) is separate from disinformation that causes “harassment” (his example was Sandy Hook truthers like Jones). In both cases, Facebook would take posts down, but Zuckerberg called the mechanisms behind doing so a “broad debate,” and drew the line at intent to do harm.

But Jewish organizations like the Anne Frank Center say that Holocaust denial does cause harm.

“There is a difference between providing a platform for free expression and knowingly spreading false information and lies,” Alexandra Devitt, Director of Communications for the Anne Frank Center, told Motherboard. “Social media gives us an opportunity for discussion, but with responsibility for not causing harm. Denying the Holocaust causes harm.”

A spokesperson for the United States Holocaust Memorial Museum directed Motherboard to a recent tweet when asked about Zuckerberg’s comments.

“Even the Nazis admitted to the Holocaust,” the Washington, DC museum tweeted.

Wednesday, Facebook said that it would begin removing misinformation that could lead to people being physically harmed. According to the New York Times, the new policy is in response to cases where rumors that spread on Facebook let to violence. In March, for example, UN investigators said that Facebook posts 'substantively contributed to the genocide in Myanmar.

Facebook still hasn’t been publicly transparent about its internal rules on content moderation. And while Motherboard recently peeked under the hood, revealing that Facebook at one point had (or still has) a threshold for Page deletion, we don’t know how moderators distinguish the acceptable conspiracy theories from the harmful ones.

“Facebook has a moral and ethical obligation not to allow its dissemination,” ADL’s Greenblatt added. “The Anti-Defamation League will continue to challenge Facebook on this position and call on them to regard Holocaust denial as a violation of their community guidelines.”