AKIPRESS.COM - Due to escalating tension between U.S. and Russia over Ukraine, NASA has cut off contact with the Russian Federal Space Agency. The order does not extend to Americans on the International Space Station, who will continue to cooperate with Russian astronauts, Gigaom reported several hours ago.

The news went out to NASA employees in a memo first reported by The Verge: “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. This suspension includes NASA travel to Russia and visits by Russian Government representatives to NASA facilities, bilateral meetings, email, and teleconferences or videoconferences. At the present time, only operational International Space Station activities have been excepted. In addition, multilateral meetings held outside of Russia that may include Russian participation are not precluded under the present guidance.”

Since closing its shuttle program in 2011, NASA has relied on Russia to ferry its crew members to the ISS. It currently pays Russia $70.7 million per astronaut. It last sent a U.S. crew member up on Russia’s Soyuz rocket on March 25 amid already tense international relations. ISS astronauts work together daily on maintenance and other missions, and the countries involved pay each other to use equipment located outside their portion of the ISS.

NASA administrator Charles Bolden testified before the House Science, Space and Technology Committee in March that tensions over Crimea would not halt NASA-Russia relations on the ISS. He said that Russia relies on the U.S. to operate essential parts of the space station, so cutting U.S. astronauts off from it would cause the entire station to essentially shut down. He described Russia as “equally worried” about the U.S. stopping its work on the ISS.

Tension between Russian and the U.S. began mounting after Crimea voted to leave Ukraine and asked to join Russia in March.