The tug of war between Russia and the United States over their space programs continues.Russia announced Tuesday that it will no longer allow the United States to use Russian-made rocket engines to launch military satellites, and does not want to extend Russian use of the International Space Station beyond 2020.

“”We are ready to deliver these engines but on one condition, that they will not be used to launch military satellites,” Deputy Prime Minister Dmitry Rogozin said.

The announcement comes a bit more than a month after the United States ordered federal agencies to stop doing business with Russia as part of sanctions against the country for annexing Crimea. For NASA, that means things like meetings and Boreal Forest research will be halted. But the sanctions also underscore just how reliant the U.S. is on Russia for large parts of the space program.

The U.S. relies on Russia to ferry astronauts to and from the International Space Station. It extended its contract with Russia to do so last month at a cost of $457.9 million. It also purchases rockets that help launch satellites and spacecraft from Russia, which has perfected an alloy mix for the engines. Rogozin said at a news conference that Russia’s announcement affects the use of MK-33 and RD-180 engines.

A NASA spokesperson said Russia has not informed the agency of its plans. An American astronaut is expected to land in Kazakhstan at 9:58 Eastern Tuesday.

NASA said in a statement, “Space cooperation has been a hallmark of US-Russia relations, including during the height of the Cold War, and most notably, in the past 13 consecutive years of continuous human presence on board the International Space Station. Ongoing operations on the ISS continue on a normal basis with a planned return of crew tomorrow and expected launch of a new crew in the next few weeks. We have not received any official notification from the Government of Russia on any changes in our space cooperation at this point.”