United Launch Alliance’s woes with its new Vulcan rocket have forced it to switch gears to only launching Atlas V rockets for now, pushing the Space Force to once again hand a national security mission over to SpaceX.

ULA’s lone launch this year was a Vulcan rocket for the Space Force. But one of its booster nozzles burned off during launch, which prompted the government to state it would hold off any further launches on ULA’s beleaguered rocket.

With its heavy backlog of national security missions on hold — all slated for Vulcan — on hold, ULA has had to switch gears to its few remaining Atlas V rockets while it works through solving the issue on the solid rocket boosters, which are provided by subcontractor Northrop Grumman. ULA’s next launch is slated for early Sunday morning from Cape Canaveral Space Force Station’s Space Launch Complex 41 on a mission to fly more of Amazon’s Project Leo satellites.

The Space Force, meanwhile, has pulled a mission that was to fly this year on a Vulcan and switched it to a SpaceX Falcon 9.

Similar to shifts it had made previously, the National Security Space Launch (NSSL) mission dubbed GPS III-8 with a GPS satellite headed to medium-Earth orbit is now slated to launch no earlier than late April from SpaceX’s facilities at Cape Canaveral Space Force Station’s Space Launch Complex 40.

It’s the fourth time the Space Force has made such a switch on task orders awarded during the NSSL Phase 2 contract between 2020-2024.

“The Space Access and NSSL teams’ primary mission is to deliver critical capabilities for the warfighter — when and where it’s needed,” said USSF Col. Ryan Hiserote in a press release from Space Systems Command. “With this change, we are answering the call for rapid delivery of advanced GPS capability while the Vulcan anomaly investigation continues.  We are once again demonstrating our team’s flexibility and are fully committed to leverage all options available for responsive and reliable launch for the nation.”

Just like the previous three switches, though, ULA has been given a future mission as a tradeoff that was originally tasked to SpaceX. So now Vulcan will get to fly the USSF-70 mission, which is slated for no earlier than the summer of 2028, giving ULA more time to fix Vulcan’s issues.

ULA first began losing the GPS satellite missions to SpaceX because of delays in Vulcan certification. Vulcan is ULA’s replacement for its already-retired Delta IV class of rockets and its remaining stable of Atlas V rockets.

Vulcan launched twice in 2024, but suffered a similar nozzle issue on one of its boosters that delayed the Space Force’s OK for it to fly national security missions until spring 2025. It then flew a flawless national security mission later in 2025, but suffered the booster issue again when it launched in February this year.

ULA and SpaceX have shifted roles since the NSSL Phase 2 contracts were originally announced. The five years’ worth of task orders were to give ULA 60% of the assignments. All of those were supposed to fly on Vulcan, with its first launches to be completed by summer 2022.

To date, ULA has only managed to fly three of those 26 missions. The first had to shift to an Atlas V rocket in summer 2024 as Vulcan awaited certification.

ULA, a joint venture of Boeing and Lockheed Martin that formed in 2006, had originally been targeting mid-2020 for Vulcan’s debut. But it faced hurdles from COVID, acquisition of engines from supplier Blue Origin, delays from customer payloads and even a fiery test stand incident that all contributed to a nearly four-year slide.

As it works through the Vulcan issues, it has this week’s Amazon Leo 5 mission with 27 satellites that’s set to be followed by another Atlas V on the Amazon Leo 6 mission later this spring.

After those two flights, ULA will be left with eight more Atlas V rockets, with two more set aside for Amazon and the other six reserved for Boeing Starliner flights.