At the end of the Cold War, U.S. military and intelligence leaders encouraged American aerospace companies to buy Russian rocket engines so that Russia would not sell them to countries like Iran, Iraq and North Korea. Based on those policies, Lockheed Martin put the Russian-made RD-180 engine on the Atlas 5 rocket in 1995. In that era, the use of Russian rocket engines was a priority, not a political concern.

Today, approximately two-thirds of our military, intelligence community, scientific and weather satellites are launched into orbit on the Atlas 5, which uses the Russian RD-180 rocket engine. United Launch Alliance, a joint venture of Lockheed and Boeing formed in 2006, has conducted more than 100 of these missions without a single failure, the vast majority with the Atlas 5.

Given the current volatility of our relationship with Russia, our nation needs to develop a reliable, American alternative to the RD-180 as soon as possible. Unfortunately, that may not be for another four to five years at best.

Congress has been debating whether we are willing to risk our military’s ability to access space before we have a domestically produced engine that has the capabilities of the RD-180. Some have pushed highly restrictive legislative limits on importing the RD-180 — thus grounding the Atlas 5 that powers vital national security launches. I have heard directly from military leaders who say we will have a multiyear gap in access to space if we allow these provisions to take force. Given these concerns, it is far too risky to ban the use of the RD-180 before we have a reliable American alternative.

I’m the first one to argue that we should not be dependent upon any foreign power for access to space — especially in the national security arena. I have already worked to secure more than $300 million in funding for the development of an American-made rocket engine. However, recklessly restricting the use of the RD-180 in the near-term will undermine both national security and the prospects for real competition in the military launch business.

Let me be clear: I understand the legitimate congressional concerns regarding relying on the RD-180 for national security launches. That said, I believe that some in Congress have overreacted with ill-conceived legislation that would restrict the near-term use of these engines — ironically weakening our national security, according to Defense Secretary Ash Carter, Air Force Secretary Deborah Lee James, Air Force Chief of Staff Gen. Mark Welsh, Director of National Intelligence James Clapper, and many officials working for them.

Sen. John McCain (R-Ariz.) pushed these restrictions in close coordination with SpaceX, which stands much to gain by eliminating competition. The SpaceX Falcon 9 rocket was recently certified for some of these launches by the Air Force, albeit under intense political pressure from the Obama administration. While SpaceX has launched several commercial payloads and has conducted six cargo flights to the International Space Station, it has suffered numerous delays and anomalies. Shortly after the Air Force’s certification of the Falcon 9, a catastrophic failure in June led to the complete loss of both the vehicle and all of its taxpayer-funded cargo, thus grounding the vehicle. The company was already over two years late developing the Falcon 9 and now has a substantial backlog of its current launch schedule, which raises the question of what the launch priorities will be if it does resume flights.

To foster such a monopoly through misguided political decisions would be a matter of considerable concern relating to national security. SpaceX has yet to undertake any form of national security launch. Yet without changes to the restrictions pushed by Senator McCain, virtually all of America’s military space missions will depend on SpaceX’s grounded rocket and its problematic launch history while the highly dependable Atlas 5 will be unavailable due to political motivations and maneuvering.

Secretary Carter and Director Clapper recently told Congress that without the Atlas 5, “we could be faced with a multiyear gap where we have neither assured access to space nor an environment where price-based competition is possible.” We simply could not and cannot allow this to happen.

Clearly, the United States needs to move as quickly as possible to develop, build and certify a safe and affordable alternative to the RD-180. Until then, I’m pleased that Congress has provided the policy guidance and legal flexibility to assure that our military has access to space, and that taxpayers can count on fair and healthy competition.

U.S. Sen. Richard Shelby (R-Ala.) is a senior member of the Senate Appropriations Committee.