Atlas V Rocket Launch
An Atlas V rocket launched from Vandenberg Air Force Base on Dec. 5 carrying a classified payload. United Launch Alliance/ODNI/NRO

The Pentagon has asked Air Force officials to review if Russian engines used in Air Force rockets could pose a national security risk to the United States, a report said on Thursday.

A Lockheed Martin Corp. (NYSE:LMT) and Boeing Co. (NYSE:BA) joint venture uses Russian-built engines on Atlas V rockets, which launch U.S. military satellites into space. But now the relationship between the joint venture and Russia has come under close scrutiny after the U.S. and Europe announced sanctions against Russia for its actions in Crimea.

The review, reported on Thursday by Bloomberg News, comes after U.S. Defense Secretary Chuck Hagel said last week at a House of Representatives meeting that there was going to be a thorough reassessment of U.S-Russia relations.

The U.S. currently contracts launches out to the joint venture group, called the United Launch Alliance, which uses the Russian made RD-180 rocket engine.

The government's concern is that it might be put in a position where it has to rely on equipment from a potential future enemy. The same concerns were raised when it was discovered that some parts of the Air Force's F-16 jet fighter were discovered to made in China. The Pentagon had to ask for a waiver for the company that made those particular parts because of their top-secret nature and foreign origin.

The current situation with Russia is different because the U.S. isn’t only concerned about national security -- the U.S. wants to place strict sanctions on Russia, and that includes ripping up existing contracts among businesses that work with Russia and Russian companies. However, Pentagon officials estimated that it would cost $1 billion and take up to five years to build the engines domestically, said Maureen Schumann, a Pentagon Spokesperson, via an email that appeared in a Bloomberg report.

Waiting in the wings is Elon Musk, co-founder of Tesla Motors Inc (NASDAQ:TSLA) and CEO of Space X, who said at a March 5 congressional hearing that the Atlas V rockets should be phased out in the interest of national security.

However, it’s also been well documented that Musk’s Space X program has its own rockets and delivery system, and it relies only on U.S. made engines. It’s also no secret that Musk wants to muscle in on Lockheed and Boeing’s $70 billion joint venture with the government.

However, he may have to wait some time, as the United Launch Alliance say it has stockpiled around two years worth of RD-180 rockets.