SpaceX made history earlier this week with a successful launch of its Crew Dragon capsule, sending it to the International Space Station where it successfully docked and allowed ISS crew members to explore its interior. It’s a major step for both NASA and SpaceX, but Russia’s space agency might not feel the same way.

Roscosmos, the state-owned space corporation of Russia, and its Soyuz rockets have been the one and only ride available to NASA astronauts since the Space Shuttle program was shut down. The U.S. pays Russia a handsome fee, hundreds of millions of dollars, every year to secure seats for NASA crew members who need to go into space. That’s about to end, and as Ars Technica reports, the public-facing smile Roscosmos is putting forth may not be entirely genuine.

Roscosmos and NASA have what might be considered a marriage of convenience. Both groups are big players in space and both have helped make the International Space Station what it is today. They have a good relationship, or at least appear to get along well, and Russia has shouldered the responsibility of getting NASA astronauts into space.

For NASA, this arrangement isn’t perfect. NASA has to pay, of course, and the actual launch of each new group of crew members is largely out of their control. Ideally, NASA would have its own vehicles that it could send to the space station whenever it needs to, and that’s what SpaceX’s Crew Dragon (and later Boeing’s Starliner) will provide.

It’s hard to know exactly what Roscomos thinks about all of this, but it’s not hard to read between the lines. During the docking of the Crew Dragon to the ISS, Roscosmos instructed cosmonaut Oleg Kononenko to remain in the Russian arm of the space station.

Roscosmos claimed that decision was made for safety reasons, later tweeting a vague congratulatory message (in Russian) to NASA. The tweet also noted “that flight safety must be immaculate.” A subsequent tweet in English congratulated NASA without mentioning its apparent safety concerns.

Later, when Crew Dragon was about to dock with the ISS, Roscosmos tweeted a self-congratulatory message highlighting the use of Russian-made gas masks by the crew members set to explore the insides of the SpaceX vehicle.

Reports out of Russia later mentioned “an unusual smell” and apparently elevated levels of isopropyl alcohol in the air of the ISS after the Crew Dragon vehicle docked. The smell was gone after the space station’s air was cycled, but the unnamed source within Russia’s space program made sure everyone knew about it.

Russia has been critical of SpaceX and Elon Musk before, and it’s no secret that some of the biggest names in Russia’s space science scene aren’t super fond of the company or its boss. NASA astronauts showing up to the space station in a SpaceX capsule probably doesn’t sit well with some of the country’s top space executives, especially when Roscosmos itself is relying on Soyuz rocket technology originally developed in the 1960s.

It’ll be interesting to see how things develop in the months and years to come. NASA’s first crewed flight of Crew Dragon is expected to come sometime this summer.