The U.S. government has suspended all contact between its space agency and the Russian space agency over the current crisis in the Ukraine, according an internal letter written by a top official earlier this week.

A memo sent out by Associate Administrator Michael O'Brien said all contact between NASA and Roscosmos and NASA has been "indefinitely suspended," with the exception of activities involving the operation of the International Space Station.

"This suspension includes NASA travel to Russia and visits by Russian Government representatives to NASA facilities, bilateral meetings, email, and teleconferences or videoconferences," says a letter written by Michael F. O'Brien, NASA's associate administrator for international and interagency relations, according to Fox News.

Last week an American and two Russian cosmonauts joined a current expedition at the ISS.

Last month, NASA Administrator Charles Bolden said to the press that he felt the U.S. and Russia's space partnership would not be affected by tensions in Ukraine.

"Right now, everything is normal in our relationship with the Russians," Bolden said at the time. "I think people lose track of the fact that we have occupied the International Space Station now for 13 consecutive years uninterrupted, and that has been through multiple international crises."

Since NASA grounded the Space Shuttle program, the U.S. has relied heavily on Russia's launch vehicles to transport astronauts to space. Bolden feels that Russians are just as dependent on the U.S. to make sure the ISS continues to run properly however, according to UPI.com.

Congress passed the final version of a bill that would send aid to the Ukraine, including mild sanctions on Russia and a $1 billion guaranteed loan.

NASA said it will be releasing an official statement soon regarding the suspension.

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