Elon Musk, the world’s richest man, endorsed on Wednesday a post on X espousing baseless antisemitic conspiracy theories that Jewish people are promoting “hatred against whites” and support bringing “hordes of minorities” into western nations, drawing condemnation from Jewish groups and praise from white nationalists and antisemites.

“You have said the actual truth,” Musk wrote in response.

It’s a baseless conspiracy theory that has inspired antisemitic and white nationalist mass shooters, including the man who killed 11 worshippers at a Pittsburgh synagogue in 2018 and another who killed 10 at a Buffalo, N.Y., grocery store last year.

The back-and-forth began when a user on X, formerly Twitter, posted a PSA from the group Stand Up to Jewish Hate challenging those who say antisemitic statements like “Hitler was right” to not do so anonymously and face the subjects of their bigotry directly. Musk responded in agreement to another user who challenged that PSA with the antisemitic conspiracy theories.

In other posts, Musk attacked the Anti-Defamation League, a leading group fighting antisemitism, with whom he has feuded in the past. He said without evidence that the organization promotes anti-white and anti-Asian bigotry, later adding “this does not extend to all Jewish communities, but it is not just limited to the ADL.”

The CEO of the ADL, Jonathan Greenblatt, wrote on X that it was “indisputably dangerous to use one's influence to validate and promote antisemitic theories.”

Musk was replaced at a meeting of CEOs on the sidelines of the Asia-Pacific Economic Cooperation summit in San Francisco on Thursday by John Kerry, President Joe Biden’s climate czar, though it's not quite clear why. The event’s organizer did not immediately return a request for comment.

Musk later met briefly with China’s leader Xi Jinping at another APEC event on Thursday.

Separately, tech giant IBM pulled their advertising from X after the left-leaning nonprofit Media Matters published a report finding IBM ads — as well as those from other brands including Apple and NBCUniversal’s Bravo television network — running next to content “that tout Hitler and his Nazi Party.” Antisemitic posts surged on X after Musk bought the platform last year and reinstated some of the most vehemently bigoted accounts. 

“IBM has zero tolerance for hate speech and discrimination and we have immediately suspended all advertising on X while we investigate this entirely unacceptable situation,” the company said in a statement to the Financial Times on Thursday.

The White House condemned Musk's social media post, calling it a "abhorrent promotion of Antisemitic and racist hate" that "runs against our core values as Americans."

“It is unacceptable to repeat the hideous lie behind the most fatal act of Antisemitism in American history at any time, let alone one month after the deadliest day for the Jewish people since the Holocaust," said White House spokesperson Andrew Bates, adding: "We all have a responsibility to bring people together against hate, and an obligation to speak out against anyone who attacks the dignity of their fellow Americans and compromises the safety of our communities.”

But the praise Musk received from some of the most bigoted actors in American politics was much louder. 

“This is the richest man in the world. And one of the top Twitter users with 160 million followers, casually drawing a link between Jewish influence and anti-white hatred,” trumpeted Nick Fuentes, a leader of an antisemitic far-right youth movement who has praised Adolf Hitler and denied the Holocaust. Fuentes marched at the deadly white supremacist rally in Charlottesville, Virginia, in 2017 and notably dined with former President Donald Trump alongside antisemitic rapper Ye, formerly known as Kanye West, last year. 

The official account for Gab.com, an antisemitic social media website used by the Pittsburgh synagogue gunman, celebrated that Musk was beginning to ask the," JQ," seemingly short for “Jewish Question," a term frequently used by antisemites.

“We’re winning hearts and minds,” Gab CEO Andrew Torba wrote on his platform.

Without addressing her boss’ endorsement of the antisemitic conspiracy theory, X CEO Linda Yaccarino posted that their company “has always been very clear that discrimination by everyone should STOP across the board.”

“When it comes to this platform — X has also been extremely clear about our efforts to combat antisemitism and discrimination,” Yaccarino wrote. “There's no place for it anywhere in the world — it's ugly and wrong. Full stop.”

Musk, who has billions in contracts with the U.S. government through his various companies, has increasingly involved himself in American politics in recent months and years, specifically the right-wing. Beyond his ownership one of the world’s most prominent platforms for politicians, journalists and activists, he attended a meeting with Senate leaders on artificial intelligence in September, co-hosted Florida Gov. Ron DeSantis’ presidential announcement, interviewed another 2024 Republican contender Vivek Ramaswamy, visited the U.S. border to discuss immigration with officials there and posts often — sometimes dozens of times a day — about the various political subjects that interest him.

On Thursday alone, he posted about the war in Ukraine, transgender medical care, why Americans were not the worst offenders in the history of slavery, immigration at the southern border, the Wednesday night pro-Palestinian protest outside the Democratic National Committee’s headquarters and New York City municipal government budget cuts.

Musk has previously defended his past posts, telling CNBC in May that he is not an antisemite, but a "prosemite."