Alabama Senator Richard Shelby speaks at the Huntsville/Madison County Chamber of Commerce Washington Update breakfast at the Von Braun Center North Hall Monday morning March 30, 2015. (Bob Gathany Photographer) (Bob Gathany)

For nearly 15 years, a Decatur-based joint venture of Boeing and Lockheed Martin has had a monopoly on launching the country's spy satellites and intelligence monitoring equipment into space. United Launch Alliance, the joint venture, has been conducting the launches using what is considered to be the most efficient and powerful rocket engine ever made, the RD-180. Except now there's one problem with the engine: It's made in Russia.

The arrangement between United Launch Alliance and NPO Energomash, the Russian maker of the RD-180, dates back to the early 1990s, when the USSR broke apart. The U.S. was concerned that brilliant rocket scientists from the Soviet Union now had lots of time on their hands. In an effort to keep them busy, the U.S. made a policy decision to allow the Russians to develop a rocket engine and that the U.S. would then buy those engines for use in its satellites, according to the office of U.S. Sen. Richard Shelby, R-Ala.

Fast-forward to today, and Moscow's aggression toward Ukraine has led lawmakers to push for the end of the U.S.'s reliance on the Russian rocket engine, although they're not fully on the same page. U.S. Sen. John McCain, R-Ariz., accused Shelby, R-Ala., of "taking care of Vladimir Putin's cronies" because of the Alabama senator's insistence on continuing to use the RD-180 in the short term through a provision in a defense spending bill at a cost of $300 million . McCain was referring to the Russian government owning NPO Energomash. The company is headed by close associates of Putin, according to Reuters.

As the crisis in Ukraine continues, SpaceX, an American company formed by PayPal co-founder and Tesla CEO Elon Musk, wants to position itself as a rival to ULA. But language in the defense appropriations bill pushed by Shelby and other senators could provide a setback for Space X. The language says that the contract can only be awarded if two companies compete for the rocket contract, and SpaceX and ULA are the only realistic bidders. ULA could sabotage the awarding of the contract by not bidding.

In the last election cycle, Shelby has received a combined $160,000 in campaign contributions from Boeing and Lockheed, who operate the joint venture. United Launch Alliance employs 1,000 people in northern Alabama, where the joint venture has a facility in Decatur that produces the Atlas V rockets used by the Air Force to launch the satellites.

The senator's office said his position is primarily due to national security concerns, not ULA's Alabama presence or the 1,000 jobs it created. They say a domestic alternative to the Russian engine is so far away that national security would be comprised if Congress follows McCain's lead to ban the RD-180 by 2019, Shelby's office said. The Air Force has launches planned out for a decade, and the RD-180 is the only option to get American spy satellites into orbit, meaning that there could be a period where no satellites are launched.

That point was cited by Defense Secretary Ash Carter and Director of National Intelligence James Clapper as rationale for continuing to use the RD-180. In a letter they sent to McCain last month, they said failing to fund additional engines would create "a multi-year gap where we have neither assured access to space nor an environment where price-based competition is possible."

But a McCain spokeswoman told AL.com in an email that no such gap exists because of language in the Senate defense spending bill.

"The Senate-passed NDAA would ensure the Department of Defense has access to two space launch providers until at least 2018, if not later," she said. "If that competitive environment is placed at risk in the coming years, Congress would be able to revisit the issue and mitigate any national security impacts."

Shelby's office said he wants to end America's dependency on the Russian-made engines as much as anyone else, noting that the senator allocated $220 million last year and $143.6 million this year for the development of an American-made engine while McCain allocated nothing this year toward a new engine.

There are a couple of issues with SpaceX becoming a competitor to ULA, according to Shelby's office. For one, SpaceX doesn't have ULA's track record, as evidenced by Sunday's failed launching of a rocket packed with supplies intended for the International Space Station (ULA has successfully launched all 67 of its rockets while SpaceX has never launched a similar payload.) And transitioning from ULA's Russian-made rocket engines to a domestic alternative isn't something that will happen overnight -- as many as five years after McCain's deadline.

At a February congressional hearing, Air Force Secretary Deborah Lee James said it could take until 2024 for the military to launch national security payloads into orbit with an American-made engine.

"You're looking at maybe six years to seven years to develop an engine, another year or two beyond that to be able to integrate," she said. "So this truly is rocket science...The 2019 date is pretty aggressive and I'm not sure that we can make it."