SpaceX has been launching civilian payloads into orbit for some time. But the company has its eyes on a much more lucrative prize: putting military satellites into space for the Air Force. And thanks to a strange confluence of circumstances, its pursuit of that goal could give it an effective monopoly over those missions, according to a Republican lawmaker.

Here's how.

SpaceX's biggest rival in the space launch industry these days is a company known as United Launch Alliance, a joint venture between the aerospace goliaths Lockheed Martin and Boeing. ULA has been the dominant player in Pentagon space launches for years, putting up all kinds of sensitive GPS and communications equipment for the military that's used to direct troops and gather intelligence.

But ULA is in a tight spot. Its main workhorse for national security launches is the Atlas V, which uses a Russian-made engine. Late last year, Congress imposed a ban on the RD-180, saying they should be phased out by 2019. ULA may not be able to get some of the engines it already ordered because of the legislation, Tory Bruno, ULA’s chief executive, said in a statement. “Not only is that anti-competitive, it puts the Air Force national security mission requirements at risk,” he said.

To replace the Russian engine, ULA has partnered with Jeff Bezos-owned Blue Origin, which is developing a new engine, and has a separate engine development project with Aerojet Rocketdyne. (Bezos also owns the Washington Post.)

The problem for ULA is that this new engine won't be certified for Air Force launches until 2022 at the earliest, Bruno told a House committee Tuesday. And ULA's other alternative for doing the launches, the Delta IV, is pretty pricey — about 30 percent more costly than the Atlas V, Bruno said. (ULA says it will eventually phase out the Delta IV.)

You could say this poses a risk for the U.S. military; ULA, the Air Force's longtime launch partner, won't have a way to put some Pentagon payloads into space between 2018 and 2022.

"We are at war. We have to have these … platforms up in the air," said Rep. Mike Rogers (R-Ala.).

Here's the twist. SpaceX's rocket, the Falcon 9, is about to be cleared by the Air Force for military launches. Final approval could come as early as June, said SpaceX President Gwynne Shotwell in Tuesday's hearing.

You can see where this is going. Could the Pentagon be trading one monopoly for another?

"The fact is, [ULA] is a monopoly today—competition is re-entering the program because SpaceX is committed to helping assure access to space,” SpaceX said in a statement.

Rogers picked up on that dynamic and questioned Shotwell about it.

"If [ULA] stops the Delta IV rocket launches," said Rogers, "is there anybody else that can compete with you for those missions?"

Shotwell struggled to answer, referring vaguely to there being international launch providers. She then went back and conceded that the Pentagon probably wouldn't trust those international services with sensitive military payloads.

That was precisely the point, said Rogers.

"You would have a monopoly, is where I'm going on this," he said.

Correction: This story has been updated to clarify that the Russian rocket used by United Launch Alliance has been banned by Congress for military missions starting in 2018. Also, ULA is not developing a new engine with Blue Origin. It has partnered with the company, which is developing its own engine. The story has also been updated to include comments from Space X and ULA.