Despite all the acrimony between Russia and the U.S. over recent decades, one area where the two nations have always got along is in space — but the latest round of sanctions imposed by Washington could change all that.

On Wednesday the White House announced it would be imposing fresh sanctions on Moscow over its role in the poisoning of former Russian double agent Sergei Skripal and his daughter, Yulia, in the U.K. earlier this year.

The latest round of sanctions, due to take effect on August 22, will impose broad restrictions on technology exports to Russia, with further sanctions set to hit Russian airlines and banks. The latest round of sanctions could block hundreds of millions of dollars in exports.

The Kremlin has strenuously denied any involvement in the incident, and on Thursday morning Russian lawmakers fumed over the latest U.S. announcement, calling it “draconian” and “absurd.”

One high-ranking Russian lawmaker then suggested hitting back at the U.S. where it hurts.

Sergey Ryabukhin, a senior Russian senator who is chairman of the Russian Federation Council’s Committee for International Affairs, said Moscow could restrict exports of RD-180 rocket engines to the U.S.

RD-180 engines power the Atlas V rocket, which is used for military satellite launches, interplanetary missions and cargo runs to the International Space Station. The Atlas V has completed more than 75 launches with no major failures to date, and is key to the U.S. space program.

This isn’t the first time RD-180s have been caught in the middle of strained U.S.-Russian relations. Back in 2014, U.S. lawmakers opted to exempt the rocket engine from a ban on Russian military technology due to it importance to the U.S. space program.

United Launch Alliance, a partnership between Lockheed Martin and Boeing, relies on the Russian-made engines to manufacture the Atlas V rocket, and any interruption of supply could impact U.S. military satellite launches.

Until 2015, ULA had a monopoly on Pentagon launches, but then Elon Musk’s SpaceX was approved as a competing provider of launch services to the military, meaning it could possibly pick up the slack should Russia follow through on banning supply of the RD-180.

Back in 2014 SpaceX argued that continuing to use the RD-180 engine was illegal in the wake of Russia’s annexation of Crimea and the fact the Energomash is state-owned. The company wanted Congress to ban the use of the rocket once the current contract ran out in 2019.

Despite Space X’s pressure, in 2016 Congress opted to extend the contract for RD-180s until 2022.

In March, ULA was awarded a $351 million contract by NASA for military launches through 2020.

SpaceX isn’t the only company looking to offer alternatives to the RD-180. Jeff Bezos’ Blue Amazon is also aiming to get into the game , with recent successful tests of its BE-4 engines. ULA is hoping to use them for its launch vehicles as early as 2020, even though they don’t offer a much power as the Russian engines.

American astronauts and Russian cosmonauts have worked side-by-side for decades, insulated from the political turmoil happening around them. This was most evident with the International Space Station, where for years U.S. astronauts were reliant on Soyuz rockets launched from Russia for access.

But such camaraderie is no more, and just this week NASA announced the names of nine astronauts who will be the first to travel to the ISS via commercial space flights on board SpaceX’s Dragon rocket or Boeing’s Starliner, scheduled to begin in April 2019.