Bill Nelson,

NASA’s administrator, said Tuesday that the agency continues its working relationship with all of the partners at the space station to ensure safe operations there.

A spokesman for the U.S. space agency didn’t respond to requests for comment on Roscosmos’s remarks. The Russian agency didn’t immediately respond to additional queries.

Roscosmos is an important member of the international group that supports the orbiting lab, where astronauts and Russian cosmonauts conduct experiments and carry out research. Roscosmos hardware has been providing boosts for the facility, which is low enough in orbit that it must periodically be lifted to maintain its altitude.

“We’re in an unknown situation here. It depends on what the Russians decide to do and how the partners decide to handle the transition,” said

Scott Pace,

who previously served as executive secretary at the National Space Council and held leadership positions at NASA.

NASA had started planning for the future of the station before Russia invaded Ukraine.

The U.S. space agency wants to extend the life of the ISS through 2030, but Roscosmos hasn’t yet committed to that date, according to a NASA report from January. Before then, NASA has said it hopes at least one other space station built by private companies will be available for use and that it can continue working with other countries.

In December, NASA said it would provide funding for three different teams that have proposed deploying private stations to orbit, including one that includes

Jeff Bezos

’ Blue Origin LLC and another with

Northrop Grumman Corp.

Blue Origin declined to comment. The company previously said its station would start operating in the latter half of this decade. Northrop Grumman didn’t specify an operational date in a December statement, and didn’t respond to a request for comment. A team including Nanoracks LLC—part of Voyager Space Holdings Inc., a space company focused on exploration—also won a funding award from NASA.

Jeffrey Manber,

president of international and space stations at Voyager, said Russia has been an invaluable part of the space station. The current situation shows the need to have multiple facilities in orbit to provide options for the U.S., he said.

Axiom Space Inc. also has permission from NASA to connect a series of modules to the International Space Station that would eventually detach to become its own facility. The Houston-based company has said future infrastructure will be ready to detach from the current space station by 2028. A spokeswoman for Axiom said it works closely with NASA.

Kathy Lueders,

associate administrator for space operations at NASA, said Monday that it would be difficult for NASA to operate the facility on its own, emphasizing the station’s international nature. Such collaboration “is what makes it such an amazing program,” she said during a briefing.

Ms. Lueders said that NASA is always looking for additional operational flexibility for the space station. She said Northrop Grumman has offered a reboost capability for the facility, while SpaceX has also been looking at additional measures.

Northrop Grumman said in February it would boost the station using one of its cargo spacecraft. The vehicle meant to conduct the operation has reached the facility, according to NASA. SpaceX didn’t respond to a request for comment.

Officials from NASA have said operations at the International Space Station haven’t been affected by Russia’s decision to invade Ukraine, and that the group of agencies behind the orbiting research facility have previously navigated geopolitical situations on the ground. Roscosmos also has said it is continuing to fulfill its obligations for the facility.

Tensions rose in November when Russia used a missile to destroy a defunct satellite in space. After the incident, those on board the International Space Station carried out emergency procedures and got into spacecraft docked to the station due to new debris that was generated. Russian defense officials defended the use of the missile, which was criticized by the White House.

Russia’s invasion of Ukraine has rippled into the space industry. Roscosmos has said it would suspend cooperation at the European launch facility located in French Guiana, where the French company Arianespace SAS has used Russian-made Soyuz rockets for missions.

Write to Micah Maidenberg at micah.maidenberg@wsj.com