The chairman of the Senate Armed Services Committee assailed Pentagon officials on Wednesday for relying on Russian rocket engines to launch American military satellites into space, arguing that the practice enriches friends of President Vladimir Putin and puts U.S. national security in jeopardy.

"Today Russia holds many of our most precious national security satellites at risk before they ever get off the ground," Sen. John McCain, R-Ariz., said at a hearing to examine military space launch capabilities.

Yet McCain said the Pentagon has actively sought to undermine the committee's direction to limit that risk and end the use of the Russian RD-180 engines by the end of this decade. McCain also blamed the U.S. contractor that acquires the engines, United Launch Alliance, and two senators who support the company, Richard Shelby, R-Ala., and Dick Durbin, D-Ill., for thwarting the committee's instructions.

Air Force Secretary Deborah James told the committee the department is working to end the use of the Russian engines as soon as possible. She said disengaging from use of the Russian engines is far more complicated than it appears. She recommended a stockpile of 18 of the RD-180s until an American-made rocket can be tested and fielded.

McCain and House Majority Leader Kevin McCarthy, R-Calif., are introducing legislation Thursday to repeal a provision in law that they say allows the unlimited acquisition and use of RD-180 engines, which are manufactured by NPO Energomash. The manufacturer is owned primarily by the Russian government and controlled by several of Putin's confidants, according to the lawmakers.

United Launch Alliance is under contract with the Air Force to launch military and spy satellites. The purchases effectively reward Putin's inner circle even as Washington continues to condemn Russia's invasion of Ukraine's Crimea region, its continued support for Syrian President Bashar Assad, and other hostile actions, the lawmakers said.

"The benefits to Vladimir Putin, his network of corruption, and the Russian military industrial complex" are well known, McCain said Wednesday. "Yet despite the availability of alternatives, a select few still want to prolong our dependence on Russia while they target our satellites, occupy Crimea, destabilize Ukraine, bolster Assad in Syria, send weapons to Iran, and violate the 1987 Intermediate Range Nuclear Forces Treaty."

Yury Melnik, a spokesman for the Russian Embassy in Washington, said Russia considers congressional discussions about the RD-180 "an internal U.S. matter" and would not comment on "specific remarks by different lawmakers."

Proponents of using the RD-180s to launch a range of national security satellites said the Russian engines fill a crucial gap while the U.S. develops and tests a domestically made rocket. Barring the purchase of the Russian engines could delay important missions during that transition period, they said, while also undercutting the competition among American companies essential to ensuring costs stay under control.

United Launch Alliance spokeswoman Jessica Rye said the company had no comment.

The debate over the Russian equipment also illustrates a longstanding tension between congressional committees that have similar yet distinct responsibilities. McCain's panel is an authorization committee that writes defense policy and approves annual military spending levels. But the appropriations committees actually allot the money, and their actions can occasionally contradict what the authorizers decided.

During a December floor speech, McCain said Shelby and Durbin, both senior members of the Senate Appropriations Committee, reversed a restriction on buying the engines in what McCain called a "triumph of pork-barrel parochialism." Their provision was added -- "in secret, with no debate," McCain said -- to a $1.1 trillion government-wide spending bill passed by Congress late last year and signed into law by President Barack Obama.

United Launch Alliance, which uses the RD-180s on its Atlas V launch vehicle, has manufacturing facilities in Decatur, Alabama. Defense industry giants Boeing, based in Chicago, and Lockheed Martin formed United Launch Alliance as a joint venture. Shelby, who faces a GOP primary challenge, helped craft the spending bill but then ended up voting against it because the bill didn't tighten the vetting process for Syrian refugees seeking to enter the United States.

Over the past two years, McCain said, his committee supported measures also approved by Congress that prohibited the Russian engines but allowed a small number to be used during the transition period if the engines were fully paid for before Feb. 1, 2014 -- just weeks before Russia invaded Ukraine.

Durbin, also speaking on the Senate floor last month, said nothing was done in secret. He said Defense Department officials told him and other lawmakers that excluding the Russian engines so quickly could leave the Air Force short of all the rockets needed to launch satellites essential to national security. Durbin also said it prevents United Launch Alliance from bidding on military work, leaving the company SpaceX as the "monopoly source for the engines."

SpaceX, a rocket and spacecraft builder, is based in Hawthorne, California, McCarthy's home state.