NASA said today that it will suspend contact with Kremlin officials over Russia's violations of Ukraine's sovereignty, according to The VergeThe move will put all joint space projects between the two nations on hold until further notice, with the important exception of missions to the International Space Station.

In an internal NASA memorandum obtained by The Verge, NASA said that the suspension includes travel to Russia, teleconferences, and visits by Russian government officials to NASA facilities. NASA is even suspending the exchange of emails with Russian officials.

In the memo, NASA administrator Michael F. O'Brien wrote:

Given Russia's ongoing violation of Ukraine's sovereignty and territorial integrity, until further notice, the U.S. Government has determined that all NASA contacts with Russian Government representatives are suspended, unless the activity has been specifically excepted.... We remain in close contact with the Department of State and other U.S. Government departments and agencies. If the situation changes, further guidance will be disseminated.

The announcement follows NASA Administrator Charles Bolden renewed push for independence from Russia, made during a hearing on NASA's fiscal year 2015 budget proposal. MSNBC reports:

During a meeting of the Subcommittee on Space to discuss that NASA budget, Bolden told the legislators if the space agency is fully funded by the Congress then the U.S. could likely end its dependence on Russia to get American astronauts to the International Space Station. He said he feels “confident” that America can again send its own astronauts into space by 2017 with that funding. Echoing sentiments made by several members of Congress at the hearing, the NASA chief added, “I do not want to be reliant on the Russians to get my crews to the International Space Station.” 

Bolden has repeatedly requested more funding from Congress to develop U.S. space taxis so that the agency can stop relying on Russian spacecraft to deliver astronauts to the International Space Station (ISS). During the hearing, he again pointed to Congress as a source of blame for NASA's reliance on Roscosmos, saying, "This committee, this Congress, chose to rely on the Russians because they chose not to accept the President’s recommendation and request for full funding for commercial crew."

Last week, Bolden stressed that he is not concerned that the astronauts will be stranded in space, and NASA today confirmed to The Verge that ISS missions are exempt from the Russia ban. Last week an American astronaut hitched a ride with Russia's soyuz spacecraft to the ISS. He joins another U.S. astronaut already on the space station, and more are slated to use Russian transport to get to the station. They all will rely on Russian spacecraft to return back to Earth. 

At least one NASA scientist sounded upset by the news. He told The Verge, "NASA's goals aren't political. This is one of the first major actions I have heard of from the U.S. government and it is to stop Science and Technology collaboration... you're telling me there is nothing better?"

NASA has not yet delivered a public statement on the news.