COLORADO SPRINGS, Colo. – The chairman of the Senate Armed Services Committee is accusing the US Air Force of misrepresenting the cost to eliminate reliance on Russian rocket engines for space launch.

During a recent hearing, Secretary Deborah Lee James testified that replacing United Launch Alliance's RD-180-powered Atlas V launch vehicle with a combination of ULA's Delta IV heavy launch system and SpaceX's newly-certified Falcon 9 could cost as much as $5 billion, Sen. John McCain, R-Ariz., wrote in a Wednesday letter to James.

But shortly before the hearing, James told the committee that splitting future launches between the two domestic vehicles would cost roughly $1.5 billion, McCain said.

James' testimony also appeared to contradict recent independent cost estimates by the Pentagon's Office of Cost Assessment and Program Evaluation, or CAPE, McCain claimed. CAPE has determined that the cost of ending reliance on Russian-made rocket engines could be similar to what the US pays today, he wrote.

"Contrary to the estimates you provided to me in private, I am left to conclude that your decision to publicly cite a figure as high as $5 billion was done so to obfuscate efforts to responsibly transition off of the RD-180 before the end of the decade," McCain wrote. "I invite you to clarify the record in the context of proposals actually being considered by the committee."

McCain also cite d an Air Force study that reportedly concludes the "least-risky alternative" would be to have Delta IV and Falcon 9 compete for national security missions, leading to cost reduction. However, the Air Force has been unwilling to share the results of the study with McCain’s staff, he wrote. He asked that the service provide the full study to the committee no later than April 20.

In addition, McCain expressed concern that Russian citizens are required to be present at the launch of each satellite that requires an RD-180-powered launch vehicle.

"This access and presence of Russian nationals to the launch vehicles of our most sensitive national security satellites raises new troubling questions and is yet another reason for ending our dependence on Russian rocket engines as quickly as possible," McCain wrote. "I question why you find it acceptable to have Russian nationals working for Roscosmos, a Russian state corporation, present at our most sensitive satellite launches."

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