On Wednesday, the Tesla and SpaceX CEO tweeted a satirical meme comparing Canadian Prime Minister Justin Trudeau to Nazi leader Adolf Hitler. The black-and-white photo of Hitler was captioned: “Stop comparing me to Justin Trudeau. I had a budget.”

Critics of the tweet immediately chimed in. Musk “must apologize immediately,” said the American Jewish Committee (AJC) on Twitter. “[He] has exercised extremely poor judgment by invoking Hitler to make a point on social media. Comparing [Trudeau] to a genocidal dictator who murdered millions is not an appropriate way to criticize policies…[it’s] an insult to those who experienced unimaginable suffering at the hands of the Nazis,” it said.

By midday Thursday, Musk—a prolific tweeter with 74 million followers who rarely deletes his posts—had removed the meme from his Twitter page without explanation.

The outspoken billionaire had tweeted the photo in response to a post from online cryptocurrency news site CoinDesk, which had posted its story about Canada sanctioning 34 cryptocurrency wallets linked to funding the “Freedom Convoy” truckers and protesters. Musk previously signaled his support for the Canadian protesters when he tweeted “Canadian truckers rule” on Jan. 27, when the demonstrations were beginning.

Musk did not respond to a request for comment. The billionaire hasn’t offered any apology as of Thursday afternoon, but instead tweeted a link to a nonfiction book called The Wages of Destruction by Adam Tooze, which details the economic history of Nazi Germany. He said, “For an in-depth explanation, read [this book].”

Prime Minister Trudeau on Monday invoked Canada’s Emergencies Act for the first time in a bid to put an end to the protests, which paralyzed the national capital Ottawa and cost the country hundreds of millions in trade daily. The temporary, sweeping rules give Canadian authorities like police and financial institutions greater power to crack down on protesters by doling out fines and criminal charges and freezing assets.

Canadian authorities have been particularly tough on freezing accounts and funds linked to the “freedom” protesters. On Wednesday, the Royal Canadian Mounted Police (RCMP) ordered all FINTRAC-regulated cryptocurrency exchanges to immediately stop transacting with 34 crypto wallets associated with the protesters. Most Canadian crypto exchanges are regulated by FINTRAC, the national financial intelligence agency. Canadian financial institutions were also caught off guard by the new rules. On Tuesday evening, Canada ordered all banks, insurance and loan providers, investment and credit firms, and fundraising platforms to freeze the accounts of customers who are “illegal” protesters or have provided funds to the same.

Last month, Musk also wrote on Twitter, “If [the] Canadian government is suppressing peaceful protests, that’s where fascism lies.”

Musk’s latest Twitter controversy comes amid his battle to persuade the U.S. Securities and Exchange Commission to distribute the $40 million in fines that he and Tesla had paid to the regulator in 2018 over misleading tweets to shareholders. Tesla attorney Alex Spiro said that the SEC “seems to be targeting” Musk and Tesla with an “unrelenting investigation” due to the tycoon’s “outspoken criticism of the government.”