The director of Russia’s space program said economic sanctions aimed at the country threaten partnerships at the International Space Station and he supports a move to end future cooperation with other agencies.

In a series of social media posts Saturday, Roscosmos general director Dmitry Rogozin shared what he claimed were replies from the respective heads of the National Aeronautics and Space Administration, the European Space Agency and the Canadian Space Agency to his demand that their countries lift sanctions against enterprises involved in the Russia space industry.

“NASA will continue to work with relevant U.S. Federal departments and agencies to facilitate continued cooperation on and operation of the ISS,” read one of the posted statements that appears to be signed by NASA Administrator Bill Nelson.A phone call to NASA on Saturday to confirm the authenticity of the letter wasn’t returned.

Questions regarding Russia’s relationship with the ISS have brewed since the country invaded Ukraine in February.Rogozin told a state-owned television network last month that Russia would end sales of rocket engines to the U.S., and Moscow canceled the launch of three dozen satellites for OneWeb, a London-based satellite internet company partly owned by the U.K. government.Rogozin will shortly submit to Russian leaders specific proposals on ending cooperation on the ISS, he said in the social media posts.

At the moment though, ISS operations seem mostly unaffected by politics on Earth. NASA astronaut Mark Vande Hei returned to earth in a Soyuz capsule on Wednesday, landing in Kazakhstan with two cosmonauts.Vande Hei spent a record 355 days onboard the ISS. Three Americans, three Russians and a German are currently based at the ISS, while Axiom Space plans to send up three space tourists and their captain as soon as April 6.NASA plans to operate the space station through 2030. SpaceX and Northrop Grumman Corp. were awarded NASA contracts on March 25 for a dozen more cargo missions to the ISS.