The head of the Senate Armed Services Committee (SASC) on June 16 downplayed the potential national security significance of NASA continuing payments to Russia to get astronauts to and from the International Space Station (ISS).

“I have a much bigger problem with the Russian rocket engine,” Chairman John McCain (R-Ariz.) told reporters at the Capitol. “I don’t see what the impact is, financially, of the Russian riding as compared with $300 million worth of rocket engines. There’s no comparison.”

McCain has been leading the charge in the Senate to reduce Air Force dependence on the RD-180 for national security space launches. He has accused the United States distributor for the RD-180, RD AMROSS, of marking up prices and lining affiliates of Russian President Vladimir Putin. The Air Force recently issued a request for proposal (RFP) as part of its plan to have a new next-generation rocket engine ready by 2019. RD AMROSS is a joint venture of RD-180 manufacturer NPO Energomash and Pratt & Whitney, a division of United Technologies Corp. [UTX]

NASA wants industry to deliver astronauts to ISS by 2017 as part of its Commercial Crew program (CCP), but is encountering hurdles thrown its way by Congress. The Senate Appropriations Committee (SAC) the week of June 8 approved a $334 million cut to CCP than NASA requested for fiscal year 2016.

In its approval of $2.5 billion for “ISS Crew and Cargo,” $895 million more than NASA requested, $378 million is for payments to Roscosmos, the Russian civil space agency. NASA spokesman Kelly Humphries said June 16 that the agency is paying Russia $63 million per seat on Soyuz for FY ’16. Humphries said NASA contracted for six seats next fiscal year, a total of $376 million. He also said NASA is slated to pay $71 million per seat in FY ’17, though this number is not finalized. At six seats, the total FY ’17 cost for rides to ISS would be $426 million, $50 million more total than FY ’16.

The House, for its part, recently passed the commerce, justice, science and related agencies (CJS) spending bill for FY ’16 that covers NASA, approving $1 billion in appropriations for Commercial Crew in FY ’16, roughly $244 million less than NASA requested.

The House voted to provide nearly $4 billion for ISS in space operations, but neither the bill nor the report breaks down a line item that mentions specific funding for “ISS Crew and Cargo.” NASA, for FY ’16, specifically requested $1.6 billion for ISS crew and cargo transportation. This includes payments for the Cargo Resupply Services (CRS) missions to ISS Space Exploration Technologies Corp. (SpaceX) and Orbital ATK [OA] are performing. The House passed bill provides $18.5 billion for NASA and roughly $3 billion for ISS operations while SAC approved $18.3 billion for NASA.

New to this year’s budget cycle, SAC moved the line item for Commercial Crew from the exploration account to the “ISS Crew and Cargo” line item under space operations. “ISS Crew and Cargo” includes funding for CRS missions, commercial crew and payments to Roscosmos for American rides to ISS on its Soyuz rockets. “ISS Crew and Cargo” also falls under the ISS funding umbrella, for which SAC provided nearly $4 billion. In addition to “ISS Crew and Cargo,” ISS operations and ISS research also falls under the ISS funding umbrella.

McCain’s counterpart in the House, Rep. Mac Thornberry (R-Texas), told reporters June 16 that U.S. dependence on Russia for space-related items is a national security issue. But Thornberry also said the challenge with paying for Russian rides to ISS is much like the RD-180 scenario: one faced with limited options.

“It ought to be a lesson for all of us about letting key capability atrophy and becoming dependent upon somebody else whose reliability can be called into question,” Thornberry said. “That doesn’t mean you snap your fingers and solve it any more than you snap your fingers and solve the Russian engine issue.”

The Defense Department has been criticized for relying too long on the RD-180 instead of developing its own rocket engine capability. The RD-180, used in a majority of U.S. national security launches, is considered reliable and cost effective.

But Russia’s annexation of Crimea has brought scrutiny from lawmakers like House Armed Services Committee (HASC) member Duncan Hunter (R-Calif.). In addition from wanting to block the Air Force from acquiring additional RD-180s, Hunter also “absolutely” believes continuing payments to Russia for rides to ISS is a national security issue.

“Relying on Russia for any type of space operations is a national security concern,” Hunter Chief of Staff Joe Kasper said June 12 in an email. “The more we rely on Russia, the less we rely on ourselves, even to the point where it might become impossible to bring ourselves back to a competitive position.”

The Senate has been debating the FY ’16 defense authorization bill, but did not take up the bill for a vote June 16. The House in mid-May passed its version of the defense authorization bill.  Thornberry said a conference report would be ready by the end of July.

Thornberry said RD-180 will be an issue discussed in conference with his Senate colleagues. The Senate’s defense authorization bill contains a provision that would allow the Air Force to procure not more than nine RD-180s in FY ’16. The House-passed authorization bill does not contain this provision.

Thornberry said his goal would be to get the U.S. off RD-180 dependence “as rapidly and as efficiently” as possible. The Air Force has warned that a potential gap in “assured access to space” may develop around the congressionally-mandated 2019 deadline for a new engine because it doesn’t think it will have the new engine ready to fly by that date and only one certified launch vehicle, provided by SpaceX, might be available at that time. Assured access is the law requiring two certified rockets to get national security space payloads into space at any one time.

DoD is debating internally whether to enact a national security waiver found in the FY ’15 NDAA that would allow it to purchase additional Russian rocket engines.

“So what’s the right balance, to push enough, but maintain that access,” Thornberry said. “That will be one of the issues we have to talk about.”