The invasion of Ukraine has sparked an ongoing battle of words between a former NASA astronaut and the leader of the Russian space agency.
Dmitry Rogozin, the head of Roscosmos, had already caused indignation over apparent threats to the International Space Station (ISS) and a suggestion that US President Joe Biden has Alzheimer's.
However former NASA Astronaut and author Scott Kelly took exception to a reply from Rogozin which called him a moron and said the death of the ISS would be on the astronaut's conscience.
That came after Kelly had suggested Russia's space programme wouldn't be "worth a damn" without foreign support.
"Maybe you can find a job at McDonald's if McDonald's still exists in Russia," the retired Navy captain wrote.
Rogozin deleted his reply, but not before Kelly got a screenshot and asked the Russian: "Dimon, why did you delete this tweet? Don't want everyone to see what kind of child you are?"
However, referring to Rogozin as Dimon - a less formal name to refer to someone called Dmitry - inflamed the situation.
"You needlessly provoke me," Rogozin replied.
"We are not familiar with you, but you address me... and call me 'Dimon', although I do not know such a treatment and I will not allow you to behave like that with me.
"You are being defiant and destructive."
He then suggested Kelly might be suffering in a similar fashion to Biden.
"Perhaps the dementia and aggression that you have developed is a consequence of the overload and stress of four flights into space," Rogozin continued.
"I invite you to undergo an examination at the Brain Institute of our Federal Medical and Biological Agency."
Kelly has continued to tweet his support of Ukraine in both Russian and English on the social media platform after Rogozin apparently blocked him.
One told Roscosmos the "special military operation" they were talking about was actually "called a war and seems to include war crimes committed by Russian troops."
Another retweeted a story about McDonald's temporarily halting its operations in Russia with the comment: "Maybe they can go to McPutins. I hear their burgers are killer."
