WTF?! Once again, Elon Musk is having a war of words with Russia, but this time the world's richest man was the subject of a veiled threat from the country's space chief. Musk's response? A tweet that read: "If I die under mysterious circumstances, it's been nice knowin ya."

The incident revolves around Musk sending Ukraine shipments of SpaceX Starlink terminals that allow its citizens to continue accessing the internet in cities under siege. Deputy Prime Minister Mykhailo Fedorov says there are now around 150,000 active Starlink users per day in Ukraine.

Musk's generous act was condemned by Dmitry Rogozin, the head of space agency Roscosmos, in the Russian's Telegram channel over the weekend. "Elon Musk is involved in supplying the fascist forces in Ukraine with military communication equipment," he wrote, describing the Ukrainian military as "Nazis."

"And for this, Elon, you will be held accountable like an adult—no matter how much [you] play the fool." The post also included a short clip of Musk and his mother arriving at the Met Gala in New York last week.

Musk tweeted a reply to Rogozin's message, writing that "The word 'Nazi' doesn't mean what he seems to think it does."

In reference to the threat of consequences, Musk also wrote, "If I die under mysterious circumstances, it's been nice knowin ya." It was obviously a tongue-in-cheek comment, but his mother, Maye Musk, did not appreciate her son's lack of concern. "That's not funny," she replied, though Musk assured her he would do his best to stay alive.

In response to Musk's tweet, Rogozin later wrote: "A billionaire from South Africa, whose family made their capital during the apartheid years, wants to explain to me, the son of a front-line soldier, a citizen of a country that lost 27 million only killed during the war against the Nazis, the meaning of the word NAZISM."

Russia has a long been suspected of assassinating (or attempting to) those it considers enemies and opponents—usually via poisoning—the most recent being opposition leader Alexey Navalny. One famous case was the 2006 poisoning of Alexander Litvinenko in the UK. The former FSB security service officer turned critic died after polonium-210, a radioactive isotope, was put in his tea. There was also the 2018 poisoning of Sergei Skripal in Salisbury, UK, which was believed to have been carried out using the Novichok nerve agent developed by Russia. Novichok was also used against Navalny.

Rogozin and Musk have clashed in the past. Russia's space chief previously warned that the ISS could crash into the earth due to sanctions placed on his country, but Musk said SpaceX could prevent such a disaster. Rogozin also had plenty to say when Musk offered to engage President Putin in unarmed combat to decide the future of Ukraine.