The former NASA astronaut involved in a war of words with a top Russian space official says he is backing away from the feud.
Scott Kelly got into a social media fight with Roscosmos head Dmitry Rogozin over Russia's invasion of Ukraine.
They traded barbs, with Kelly telling Rogozin he might still be able to get a job in McDonald's, providing it still existed in Russia.
Rogozin suggested the retired US Navy captain was suffering from dementia, and called him a moron.
However, CNN reported the US space agency had requested that Kelly stop because it could damage the long-standing International Space Station (ISS) partnership between the countries.
That had even led to speculation last week that Mark Vande Hei, who this week beat Kelly's record for longest continuous time spent in space by an American, could be left stranded.
A video showing this possibility was shared by Rogozin, but was later clarified as a joke.
The request to Kelly and other former astronauts came via email, CNN reported.
"As Americans, each of us enjoys freedom of speech and you are all empowered to speak your mind.
"However, please know that as former NASA astronauts, your words carry additional weight and attacking our Russian partners is damaging to our current mission.
Kelly confirmed to the news channel he had "backed off Rogozin".
"I didn't have to, but I respect NASA, NASA's position and the [official] that sent it," Kelly said. He will, however, keep opposing the war and sharing his support for Ukraine.
NASA intends to keep the ISS operating until 2030, but Russia's agreement runs out in 2024 and so current sanctions on the country may yet have a long-term impact.
However the agency hopes the ISS will remain the "flagship model for international cooperation", it said.
"For over 20 years, the International Space Station partnership has operated successfully, and nothing has changed in the last three weeks," the manager of NASA's ISS program, Joel Montalbano, said.
"We are aware of what's going on, but we are able to do our jobs to continue operations."
Kelly has also returned a medal he received from Russia for flights aboard the country's Soyuz spacecraft.
"Mr Medvedev, I am returning to you the Russian medal 'For Merit in Space Exploration,' which you presented to me," Kelly tweeted.
"Please give it to a Russian mother whose son died in this unjust war. I will mail the medal to the Russian embassy in Washington. Good luck."
Kelly's tweet, in Russian, was a response to former Russian President and Prime Minister Dmitry Medvedev, who tweeted on International Women's Day: "Happy Holidays, dear women! Love, happiness and health."
