Russia’s war reaches into space, leaving an American astronaut potentially stranded.

ABC News reports on an unintended consequence of the war in Ukraine that’s creating a tricky situation far overhead. American astronaut Mark Vande Hei, currently serving aboard the I.S.S., is supposed to catch a ride down to Kazakhstan with two Russian cosmonauts in three weeks. But now, due to sanctions, Russia is saying the American will have to find his own way down:

The ISS is divided into two sections: the Russian Orbital Segment operated by Russia and the United States Orbital Segment run by the U.S. American and Russian astronauts were the first to step inside the ISS in 1998.

From there, the partnership has continued. When the U.S. shuttle program ended in 2011, U.S. astronauts like Cady Coleman relied exclusively on Russian rockets to get her on board the station.

Coleman said that American astronauts and Russian cosmonauts would cooperate on everything from life-or-death missions to the mundane.

“I was up there with the three Russian cosmonauts,” said Coleman.”[We] share a goal of exploring space … and that goal doesn’t change whether we’re on the Earth or living up on the space station.”

Astronaut Mark Vande Hei, who holds the ongoing record for longest space flight, is set to end his 355 days in space in just three weeks. The plan is for him to land in Kazakhstan with two Russian cosmonauts on a Russian spacecraft.

But unprecedented sanctions against Russia could put Vande Hei’s return on hold. After Russia invaded Ukraine nearly two weeks ago, President Joe Biden announced new sanctions, including cutting more than half of Russia’s high-tech imports.

Dmitry Rogozin, the head of Russia’s Space Agency and a close ally to Russian President Vladimir Putin, responded to Biden in a series of hostile tweets. On Feb. 26, he posted a video in Russian that threatened to leave Vande Hei behind in space and detach Russia’s segment of the space station altogether.

Although war continues to wage on Earth, Kelly said he hopes that the U.S.-Russian partnership in space can be mended.

“I’ve known [people at the Russian Space Agency], many of them for well over two decades, I trust them. I’ve literally trusted them with my life before,” said Kelly, who added that the U.S. should still “prepare for the worst” and “hope for the best.”