SpaceX founder Elon Musk participates in a discussion during the 2014 annual conference of the Export-Import Bank (EXIM) April 25, 2014 in Washington, DC. Musk said SpaceX would file a lawsuit against the U.S. Air Force on shutting out private companies for launching national security related rockets. (Alex Wong/Getty Images)

A U.S. Court of Federal Claims judge issued an injunction late Wednesday prohibiting a joint venture between Lockheed Martin and Boeing from proceeding with plans to buy Russian-made rocket engines.

Judge Susan G. Braden’s ruling came after SpaceX, a California-based rocket company, sued the federal government Monday, protesting the Air Force’s award of a lucrative space contract, saying it should have been competitively bid.

In the suit, SpaceX criticizes United Launch Alliance (ULA) for using Russian engines in some of its rockets, which SpaceX founder Elon Musk said might be a violation of U.S. sanctions and was unseemly at a time when Russia “is the process of invading Ukraine.”

Musk alleged that the deal would benefit Dmitry Rogozin, the deputy prime minister who heads the Russian defense industry and is named by the U.S. government in the sanctions.

In reaction to the sanctions, Rogozin tweeted: “After analyzing the sanctions against our space industry, I suggest the U.S. delivers its astronauts to the ISS [International Space Station] with a trampoline.”

Braden’s ruling prohibits ULA from making payments to the Russian engine manufacturer.

The contract, for 36 rockets to launch defense payloads, such as satellites, was awarded to ULA — a 50-50 venture of Boeing and Bethesda-based Lockheed — on a sole-source basis in December. By 2030, the Pentagon expects to spend almost $70 billion on the program.

At a news conference last week announcing the suit, Musk, the entrepreneur who co-founded PayPal and Tesla Motors, said SpaceX could provide rockets at considerably lower cost than ULA. Since then, he has gained the support of some members of Congress, including Sen. John McCain (R-Ariz.), who have called for increased competition in the awarding of large multiyear contracts.

“This is not SpaceX protesting and saying these launches should be awarded to us,” Musk said at the news conference. “We’re just saying these launches should be competed. If we compete and lose, that’s fine. But why would they not even compete it? That doesn’t make sense.”

In a statement issued this week, ULA said it is “the only government certified launch provider that meets all of the unique . . . requirements that are critical to supporting our troops and keeping our country safe.”

A rigorous acquisitions process “saved the government and taxpayers approximately $4 billion while keeping our nation’s assured access to deliver critical national security assets safely to space,” the company said.