WASHINGTON — In a surprise move, the two losing teams for the U.S. Air Force’s T-X trainer competition have decided not to protest the service’s decision to award the competition to the Boeing-Saab team.

Spokesmen from the Lockheed Martin-Korean Aerospace Industries team and the Leonardo DRS group issued statements Thursday confirming they would not protest the contract, which could be worth up to $9.2 billion to produce 351 training jets for the U.S.

Traditionally, large defense contracts are challenged by the losers as a last-ditch effort to find a flaw in the winning bid that could re-open the competition. However, service officials previously stated they felt that repeated interactions with industry throughout the competition, as well as lessons learned from previous programs, would insulate T-X from a big protest.

The Boeing-Saab collaboration is a clean-sheet design to replace the service’s aged T-38 aircraft. Lockheed and KAI were offering the T-50, while Leonardo DRS was offering the T-100, a variant on its M-346 trainer.

Under the initial $813 million award, Boeing is responsible for delivering five T-X aircraft and seven simulators, with the first simulators arriving at Joint Base San Antonio-Randolph, Texas, in 2023.