Elon Musk’s space transport company SpaceX has won a temporary injunction against the United Launch Alliance, a joint venture of Lockheed Martin and Boeing, barring it from purchasing any more Russian-made engines it uses to send U.S. Air Force satellites into orbit with its Atlas V rockets.

SpaceX argued two points in the lawsuit.

For one, SpaceX says that the Russian engines ULA uses to launch its satellite payload fall under the trade sanctions the U.S. has put on Russia over the past month. The RD-180 engine is built by NPO Energomash, a Russian manufacturer that specializes in rocket engines. The massive engines propel the ULA Atlas V during its first stage of launch.

Musk says the ULA rockets send “hundreds of millions of dollars” to Russia, particularly to Russian Deputy Prime Minister Dmitry Rogozin, the man at the head of the country’s defense industry.

“How is it that we're spending hundreds of thousands of dollars in U.S. taxpayer money (on the RD-180s) at a time when Russia is the process of invading Ukraine?” Musk said. “It would be hard to imagine that Dmitry Rogozin is not benefiting personally from the dollars that are sent there.”

Rogozin was directly targeted by the recent round of U.S. sanctions meant to hurt those close to Putin. He’s been a vocal critic of the sanctions in the past and took to Twitter to shoot criticism back at the injunction decision, with a little bit of unsettling humor:

“After analyzing the sanctions against our space industry I suggest the U.S. deliver its astronauts to the ISS with a trampoline.”

Musk is also after a ULA contract. He criticized the U.S. government for awarding a 36-rocket contract to ULA last week, saying his company should have been able to compete for the contract because they can fulfill it for much cheaper. Musk sought a ruling on the ULA contract, but he’ll have to wait.

The injunction stops RD-180s at customs for now, but it doesn’t say anything about the lawfulness of ULA’s contract with the Air Force. It also doesn’t stop the ULA from getting engines or parts it has already paid for from NPO Energomash. A ULA spokesman told WESH Orlando that the company had enough Russian engines here in the U.S. to launch Atlas rockets for at least the next year, but not enough to fully honor the most recent contract it signed with the U.S. government.

The ULA isn’t happy about Musk’s entrepreneurial intervention, claiming it could hurt national security. ULA’s general counsel, Kevin MacCary, had this to say about the injunction:

“ULA is deeply concerned with this ruling and we will work closely with the Department of Justice to resolve the injunction expeditiously. SpaceX’s attempt to disrupt a national security launch contract so long after the award ignores the potential implications to our National Security and our nation’s ability to put Americans on board the International Space Station.”

The ban on RD-180 engines and parts will be in effect until the Obama administration can prove their purchase does not violate U.S. sanctions on Russia.