NASA spokesperson Bethany Stevens wrote on X that a transfer tunnel on the Zvezda service module has suffered cracks and leaks for an extended period.
"The cracks have been a concern that NASA has closely examined," Stevens wrote on Friday, saying that new leaks are forcing Russia's Roscosmos to carry out extensive repair work.
As a precaution, four astronauts were ordered to don spacesuits and move to the docked Crew Dragon spacecraft.
After an initial effort, they returned to the station.
