“I hereby challenge Vladimir Putin to single combat,” Musk wrote on Twitter Monday. “Stakes are Ukraine.”

Musk wrote out both Putin’s name and the word “Ukraine” in Cyrillic script. But while Putin’s name was written out in Russian, “Ukraine” was written in Ukrainian, a show of support from the world’s richest man toward the plight of Ukrainian citizens after Russia’s unprovoked invasion of the country over two weeks ago. 

The tweet has yet to receive a response from Putin, but Russian government officials have been happy to respond in his stead.

“You, little devil, are still young,” tweeted Dmitry Rogozin, head of Russian space agency Roscosmos. “Compete with me weakling. It would only be a waste of time.”

Musk has been remarkably forthcoming and public about his endorsement of Ukraine and criticism of Putin, and his support has not been limited to provoking the Russian president to duel him on Twitter. The Tesla and SpaceX CEO has not been afraid to use the vast array of resources at his disposal to help the dogged Ukrainian resistance movement and besieged citizens.

Days after the invasion, Musk accelerated a planned rollout of internet coverage from his satellite internet company Starlink to Ukraine, after a public request by Ukrainian Vice Prime Minister Mykhailo Fedorov. Musk and Fedorov claimed that expanded Starlink coverage would give Ukrainian forces a tactical advantage over the invading Russian army. Satellite dishes required to make the Starlink service work started arriving just one day after Musk’s announcement.

Fedorov seems to be on Team Elon in the possible Putin-Musk showdown. “I am sure that @elonmusk can send Putin to Jupiter,” Fedorov replied to the original tweet, adding an image of Putin locked in a spaceship en route to the planet.

Musk’s original tweet has received over 200,000 likes, but in typical Elon fashion, the billionaire businessman has been unable to avoid stirring up controversy.

Just a few hours before issuing the challenge to Putin, Musk tweeted a meme with the words “I support the current thing” circling an image of the Ukrainian flag, apparently mocking people’s inclination to show support for any topic that dominates the news cycle at a given time.

The meme did not go over well with Musk’s supporters, with some calling it “insensitive” and “tone-deaf.” Others seemed to find the meme, which garnered more than 450,000 likes, refreshing and humorous.