LOS ANGELES — After insisting that space relations wouldn’t be altered by earthly politics, NASA on Wednesday said it was severing ties with Russia except for the International Space Station.

NASA employees can’t travel to Russia or host visits until further notice. They’re also barred from e-mailing or holding teleconferences with their Russian counterparts because of Russia’s actions in Ukraine, according to a memo sent to workers.

Activities related to the space station are exempt. NASA and Russia’s space agency will “continue to work together to maintain safe and continuous operation” of the space station, NASA said in a statement released late Wednesday.

Since the retirement of the space shuttle, NASA has depended on Russia to hitch rides to the giant orbiting outpost, paying nearly $71 million for a seat on the Soyuz.

A Russian rocket last week delivered three astronauts, including American Steve Swanson, to the space station. The laboratory is a partnership of the U.S., Russia, Europe, Japan and Canada.

The move comes after reassurances U.S.-Russian space relations were fine despite tensions over Ukraine.

“Right now, everything is normal in our relationship with the Russians,” NASA Administrator Charles Bolden said March 4.

NASA reiterated the sentiment last week after Russia annexed the Crimean Peninsula from Ukraine.

“We do not expect the current Russia-Ukraine situation to have an impact on our long-standing civil space cooperation with Russia, which goes back decades,” an agency statement said.