Russia to Halt Export of RD-180 Engines for MilSat Launches and Questions ISS Future, SpaceRef Business

"The escalating war of words between Russia and U.S. just hit home hard for the Air Force and United Launch Alliance (ULA) with the news today that Russia would no longer supply RD-180 engines for export to the U.S. if used by the Pentagon."

Moscow to ban US from using Russian rocket engines for military launches, Russia Today

"Moscow is banning Washington from using Russian-made rocket engines, which the US has used to deliver its military satellites into orbit, said Russia's Deputy PM, Dmitry Rogozin, who is in charge of space and defense industries. According to Rogozin, Russia is also halting the operation of all American GPS stations on its territory from June 1. Russia currently hosts 11 ground-based GPS stations, the Deputy PM said."

United Launch Alliance Statement on Russian Statements

"ULA and our NPO Energomash supplier in Russia are not aware of any restrictions. However, if recent news reports are accurate, it affirms that SpaceX's irresponsible actions have created unnecessary distractions, threatened U.S. military satellite operations, and undermined our future relationship with the International Space Station."

NASA Statement on News Reports Regarding Russian Space Statements

"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 tonight (at 9:58 p.m. EDT) and expected launch of a new crew in two weeks. We have not received any official notification from the Government of Russia on any changes in our space cooperation at this point."