Russia has appeared to threaten to leave an American astronaut on board the International Space Station (ISS) as revenge for US sanctions over the Ukraine crisis.
A video shared on Twitter shows two Russian cosmonauts appearing to wave goodbye to American astronaut Mark Vande Hei as Russia's segment of the space station detaches from the rest.
The video was shared on the Nasa Watch Twitter account, which said the video had been made by Roscosmos, the Russian space programme, whose head is Dmitry Rogozin, and posted on Telegram.
Nasa Watch shared it with the caption: "Russian gov't-controlled RIA Novosti @rianru posted a video on Telegram made by @Roscosmos where cosmonauts say goodbye to Mark Vande Hei on #ISS, depart, and then the Russian segment detaches from the rest of ISS."
Vande Hei, 55, is due to return from the ISS along with the two Russian cosmonauts on board a Russian space craft at the end of the month, after spending nearly a year on the space station.
But their return comes amid the crisis in Ukraine, which has seen the US sanction Russia for its human rights violations.
The threat is not the first to come from Rogozin, who had warned that Western sanctions against Russia could cause the ISS to crash.
Rogozin said some of the sanctions would disrupt Russian spacecraft services the ISS which could potentially affect the Russian segment of the station.
He warned this could cause the structure to "fall down into the sea or onto land".
The apparent threat to Vande Hei has sparked anger, with his family branding it a "terrible threat", and one retired astronaut saying it had "crossed the line".
Vande Hei's mother Mary, 77, told The Mail on Sunday: "It's a terrible threat. When I first heard it I did a lot of crying. It's very troubling. We are just doing a lot of praying.'
She added: "It is really a shame that it's been politicized like this. It's quite a shock. His wife, Julie, is very worried in Texas. It's very hard for her right now."
Retired astronaut Scott Kelly told the Wall Street Journal: "It kind of enraged me that the country that we had been in this international partnership for 20 years would take the time to make a video to threaten to leave behind one of the crew members they are responsible for.
"They agreed to be responsible for his safety, getting him to the space station and getting him home. For me, that kind of just crossed the line."
However, NASA has reportedly said it is confident Vande Hei will return as planned, with the Russian Soyuz spacecraft still scheduled to return to earth on 30 March.
Vande Hei joined the two Russian cosmonauts last April and on his return will hold the American record for the longest single human spaceflight mission of 355 days.
Watch: Russia's war casts doubts on space missions