NEW YORK, NEW YORK – MAY 02: Elon Musk attends The 2022 Met Gala Celebrating “In America: An Anthology of Fashion” at The Metropolitan Museum of Art on May 02, 2022 in New York City. (Photo by Theo Wargo/WireImage)

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Elon Musk is denying a report by Eurasia Group founder and political scientist Ian Bremmer that the SpaceX and Tesla CEO recently spoke with Russian President Vladimir Putin about “the minimum the Russian president would require to end the war.”

Bremmer’s note went out earlier this week to clients. Investor Sven Henrich asked Musk, via his Twitter account “@northmantrader,” if the report was true. Musk responded in a tweet on Tuesday: “No, it is not. I have spoken to Putin only once and that was about 18 months ago. The subject matter was space.”

Later on Tuesday, Bremmer doubled down, writing that Musk had told him that he spoke directly with Putin and the Kremlin about Ukraine.

CNBC reached out to Eurasia Group and SpaceX but neither were immediately available to comment.

As CNBC previously reported, Musk posted a series of tweets Oct. 3 seeking support for his opinion on the best outcome for Russia’s war on Ukraine.

Musk proposed UN-supervised votes in Ukraine about whether certain regions of the nation under siege should join Russia. He also said Ukraine should hand Crimea over to Russia and that the nation should then remain “neutral” rather than aligning with either NATO or Russia.

Since those tweets, Musk has continued to promote the idea, on Twitter, that some Ukraine citizens would prefer to, and vote to, join Russia.

Kremlin officials praised Musk for his opinion, but Musk drew sharp criticism from many others, including Ukraine President Volodymyr Zelenskyy, Sen. Lindsay Graham, R-S.C., and Russia-born human rights activist and former chess champion Garry Kasparov.

Kasparov, who sought to block Putin’s rise to power and was jailed and beaten for his activism before fleeing the country, described Musk’s plan as a “repetition of Kremlin propaganda.”

And Ukraine’s outgoing ambassador to Germany, Andrij Melnyk, wrote in response to Musk’s tweets: “F— off is my very diplomatic reply to you.”

Musk had previously earned hero status in Ukraine because his company SpaceX enabled its Starlink satellite internet service to keep parts of the country online beginning in the early days of the conflict.

Publicly opining on war could prove risky for Musk and SpaceX, said J2 Ventures founder and managing partner Alex Harstrick. Before starting the fund, Harstrick was an Army intelligence officer who deployed to both Afghanistan and Iraq with special operations units.

“Any company that sells in a significant way to the United States of America, and specifically the Department of Defense, has to acknowledge that its CEO has a responsibility to make sure that what they are talking about in any public disclosure is consistent with the values of the United States,” Harstrick told CNBC’s “Squawk Box.”

SpaceX has notched federal contracts worth more than $10.5 billion since 2003, according to data tracked by Deltek’s GovWin and viewed by CNBC. If the leaders of a defense contractor are seen as interfering with diplomatic efforts by the U.S., government agencies may be hesitant to work with them when alternatives are available, he suggested.

Musk has also recently sounded off, in an interview with the Financial Times, about his vision for resolving China’s conflict with Taiwan. Qin Gang, China’s ambassador to the U.S., thanked Musk for the idea in a tweet.