Astronauts on board the International Space Station have now been told by NASA to “end the safe haven procedures and return to planned operations aboard the International Space Station.”

This comes after NASA instructed astronauts onboard the International Space Station to prepare to evacuate following worsening air leaks.

“The Zvezda service module transfer tunnel, known as PrK, has suffered from cracks and leaks for some time, and has been mitigated by Roscosmos as much as possible to date,” Bethany Stevens, a spokesperson with NASA posted to X.

The four astronauts of NASA’s Crew-12 mission on the station – two U.S. astronauts, a French astronaut and Russian cosmonaut – got orders from NASA mission control at 9:04 a.m. ET Monday (1304 GMT) to enter their Crew Dragon spacecraft docked to the station and don their spacesuits in case the air leak warrants an emergency evacuation, a NASA official said.

“The cracks have always been a concern that NASA watches very closely. NASA and Roscosmos have been working to determine the root cause of the cracks, and Roscosmos manages the issue through operational mitigation measures and periodic partial-repair efforts,” Stevens wrote.

NASA and Russia’s space agency Roscosmos, the station’s two primary operators, have debated for months over the cause and potential fixes of small air leaks aboard Russia’s Zvezda service module, a key structure of the football field-sized laboratory.

The air leaks have been relatively minor in recent months but escalated on Monday from a pound of air per day to two pounds, according to a senior NASA official who asked not to be named.

• With files from Reuters