Elon Musk's suggestion that Crimea become an official part of Russia to avoid an escalation of the war in Ukraine has sparked a spat with presidents and diplomats.
The Tesla billionaire tweeted his plan for peace in four bullet points, suggesting referendums in the now-annexed regions of Ukraine be redone under UN supervision, and that Crimea become "formally part of Russia as it has been since 1783".
Luhansk, Donetsk, Kherson and Zaporizhzhia were declared as part of Russia on Friday, after Moscow-run ballots which have been declared a sham by the West and Ukraine, with reports people were made to vote at gunpoint.
Crimea was taken over by Russia in 2014, after a referendum which was also globally rejected.
In a Twitter poll, Mr Musk posed the question of whether "the will of the people who live in the Donbas and Crimea should decide whether they're part of Russia or Ukraine".
Ukrainian President Volodymyr Zelenskyy responded with his own poll: "Which Elon Musk do you like more? One who supports Ukraine, or one who supports Russia?"
Mr Musk replied he "still very much support[s] Ukraine" but feared the harm that would be caused if the war escalated.
Ukraine's outgoing diplomat in Germany Andriy Melnyk gave a "very undiplomatic reply". He told the billionaire to "f*** off".
Lithuania's President Gitanas Nausėda responded: "When someone tries to steal the wheels of your Tesla, it doesn't make them the legal owner."
The referendums in what amounts to about 15 per cent of Ukraine's territory have been declared illegal by UN secretary-general António Guterres.
The four regions were formally announced as part of Russia by Vladimir Putin in a ceremony in Moscow on Friday.
Ukraine has vowed to recapture the regions, which are currently the scene of heavy fighting.
In a statement last week, the Ukraine Foreign Ministry said the votes had no implications for Ukraine's "administrative-territorial system and internationally recognised borders".
