The “Mr. Tesla,” Elon Musk, who heavily funds voter outreach in support of Donald Trump‘s re-election bid, has ongoing contact with Russia’s most powerful man, as reported by the Wall Street Journal.

The world’s wealthiest person and the top sponsor of U.S. space efforts is in regular communication with his “great adversary”: Russian President Vladimir Putin. Musk did not comment on the American report, while the Kremlin stressed that the two men only had a single phone call about space-related matters.

Musk and Putin’s conversations have been confirmed by several current and former officials from the U.S., Europe, and Russia, touching on sensitive topics, business interests, and geopolitical issues.

According to the American report, citing two reliable sources, at one point Putin asked Musk to avoid activating his satellite internet service, Starlink, over Taiwan to accommodate Chinese leader Xi Jinping.

As a prominent backer of the Republican candidate’s campaign, Musk could potentially play a role in a Trump administration should Trump return to the White House.

While the U.S. and its allies have isolated the Russian president in recent years, Musk’s frequent secret conversations with Putin might strengthen Trump’s expressed desire to negotiate on major issues.

These contacts also raise potential national security concerns. Musk has deep business ties with the U.S. military and intelligence services, providing him with unique access to some of America’s most sensitive space programs. His aerospace company SpaceX, which operates Starlink, won a classified $1.8 billion contract in 2021 and serves as the primary rocket launcher for the Pentagon and NASA.

Furthermore, Musk holds a security clearance that grants him access to classified information.

Several White House officials told the WSJ that they were unaware of Musk’s relationship with the Kremlin. The matter is especially sensitive given Musk’s growing involvement in Trump’s campaign and the upcoming presidential election on November 5.

Musk did not respond to the newspaper’s request for comment. Recently, he called criticism of him being a “Putin apologist” “unreasonable,” adding that his companies “have done more to undermine Russia than anything else.” During a campaign event in Pennsylvania last week, Musk emphasized the importance of government transparency and highlighted his own access to government secrets.

An individual familiar with the conversations said the U.S. government faces a serious dilemma, as it depends on the South African-born billionaire’s technologies.

His company SpaceX launches national security satellites into orbit and is the organization NASA relies on to transport astronauts to and from the International Space Station. “They don’t like this,” the source said, referring to Musk’s contacts with Putin, and noted that there have already been warnings from the government about possible security breaches by Musk.

Meanwhile, Kremlin spokesman Dmitry Peskov stated that Moscow’s only contact with Musk was through a phone call, during which he and Putin discussed “space as well as current and future technologies.” Besides this single phone interaction, Peskov said Putin and Kremlin officials have not had regular talks with Musk.

At the same time, a Trump campaign representative described Musk as “a once-in-a-generation industry leader” and noted that “the federal bureaucracy could certainly benefit from his ideas and efficiency.” “As for Putin,” the representative continued, “there is only one candidate in the race during whose term the Russian president did not invade another country, and that is Trump.”