WASHINGTON — With the Senate's passage of the annual defense policy bill Tuesday, an accord was formed between senators warring with each other over the United States' continued use of Russian RD-180 engines.

Senate Armed Services Chairman John McCain, R-Ariz., gave up on the bill's all-out ban on the engines and acceded to an amendment from SASC member Bill Nelson, D-Fla., that sets Dec. 31, 2022, as the end date for their use and caps the number the military can use at 18. McCain and his opponents on the issue, who advocate for more flexibility as the military develops a US-made replacement, all claimed victory after the amendment passed.

McCain thanked Nelson for the compromise and said it had cleared the way for the 2017 National Defense Authorization Act's (NDAA) broad 85-13 approval.

"I supported this compromise because it contains a legislative cutoff date for the use of Russian rocket engines," McCain said in a statement. "It does not alter other important space launch provisions in the NDAA. It provides for a sustainable path to achieve the broadly shared goal of assured access to space, competition in national security space launch, and ending our dependence on Russian engines."

Key appropriators Sens. Dick Durbin, D-Ill., and Richard Shelby, R-Ala., stood against the 2017 National Defense Authorization Act’s initial ban on the RD-180 engine. Durbin said on the Senate floor that talks to resolve the impasse included Senate Appropriations Committee Chairman Thad Cochran, R-Miss., and he called Nelson called a "bridge over troubled water," on the "divisive" issue between the two committees.

"We never want to get to the position that we just have one rocket company, because if something happened, you want to have a backup," Nelson said.  "We have got to get satellites into space to protect our national security, and we've got to do it over this period of time from now until the end of 2022."

The RD-180 is a Russian-produced element to the Atlas V launch vehicle — key to the United Launch Alliance, a joint venture of Lockheed Martin and Boeing. The compromise language says the Russian engines may be used only for launches in the Phase 1(a) and Phase 2 Evolved Expendable Launch Vehicle procurements; Phase 2 is set to run through 2022.

Advocates for more flexibility with the RD-180 argued that ending its use would endanger the military's ability to launch national security satellites and, before US alternatives are fully developed, cost taxpayers millions.

The dispute between the Pentagon and Capitol Hill over the RD-180 had become ugly, as McCain had accused his colleagues of fueling the interests of Russian President Vladimir Putin. However, Air Force Chief of Staff Gen. Mark Welsh said in an exclusive interview with Defense News on Monday that the debate between the Pentagon and the Hill had been "healthy" and "positive."

"We don't have to agree," Welsh said. "Our job is to provide the best military advice we can give based on the reality of the time. And if Congress disagrees with it, they make a decision about what they will authorize and appropriate, and we move onto the next annual cycle. I don't have any issue with debate and disagreement with the Congress. That's part of the system."

"Bottom line is everybody wants two or more viable launch systems so we have competition and save money over time for the American people," Welsh said. "Everyone wants to get off the RD-180 engine, the Russian-built engine, as soon as we possibly can. Everybody wants the same things. But there are disagreements, from all parties, on the best way to get from here to there."

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