Supporters of the U.S. Air Force’s A-10 Warthog attack jet celebrated in February when the Pentagon announced that the flying branch would delay retiring the heavily-armored, gun-armed planes until 2022, eventually replacing the A-10 squadrons one at a time with units flying the new F-35 stealth fighter.

Previously, the Air Force planned to fully retire all 300 A-10s by 2018. Congressional and public opposition—and the fact that the Pentagon has recently deployed A-10s to battle Islamic State and to deter Russia—compelled the Air Force to bump back the twin-engine jet’s final flight. “The budget defers the A-10’s final retirement until 2022, replacing it with F-35 Joint Strike Fighters on a squadron-by-squadron basis, so we’ll always have enough aircraft for today’s conflicts,” Defense Secretary Ashton Carter said.

But a planning document the Air Force published in mid-February reveals that 2022 is the flying branch’s deadline for the last A-10 retirement, not the first. In fact, according to the document, the first A-10s—those currently with the Air National Guard in Indiana and the Air Force Reserve in Kansas—will bow out as early as 2017. Active-duty Warthogs in South Korea and Arizona would cease flying as early as 2018, followed by their Guard counterparts in Maryland in 2019. The last A-10s—in Idaho, Michigan, Arizona and Georgia—would retire in 2020 and 2021.

To be clear, for Warthog-advocates the Air Force’s retirement plan is an improvement over the 2013 plan, which had the A-10 ceasing operation in 2018. But having received new avionics, weapons and wings, the A-10s in theory are capable of serving into the 2030s. And in any event, the F-35 is too fast, flimsy and lightly-armed to fully replace the rugged Warthog on any schedule.

It’s possible—even likely—that Congress will alter the Air Force’s plan when it considers the 2017 budget later in 2016.

David Axe is a contributor to War is Boring, where this article first appeared.

Image: Flickr/U.S. Air Force.