When Defense Secretary Ash Carter earlier this month announced the A-10 Warthog wasn't retiring until 2022, pilots, officials and enthusiasts of the gunship rejoiced. But some advocates of the aircraft are wary of the progress, given the Air Force's new proposal to begin divesting the aircraft as early as 2018.

Budget documents from the fiscal 2017 request show the Air Force plans to begin moving out A-10 squadrons in increments between 2018 and 2022, "to make room for F-35 squadrons standing up," over that time period, Air Force officials told Air Force Times.

"This is just a request so nothing can be made formal without Ccongressional approval," the official said.

The annual request, called the Force Structure Action plan, also calls for other aircraft to move to bases where the A-10 once hailed from.

For example, the document shows Whiteman Air Force Base, Missouri, would be one base to phase out of 27 A-10s by 2018; the base would replenish their inventory instead with 27 F-16s.

The Air Force also plans to remove 24 A-10s by fiscal 2019 from overseas contingencies in the Pacific, the official said.

The Air Force's FY17 Force Struction Action plan proposes that A-10s leave the flight line sooner than 2022.

Photo Credit: Air Force

From a deployment standpoint, the service has been providing theater security package rotations, or TSP, of A-10s in two- to five-month increments for missions such as Operation Inherent Resolve against the Islamic State group in Iraq and Syria, as well as to Europe under Operation Atlantic Resolve to reassure partners and allies under a resurgent Russia.

Twelve A-10s and airmen with the 75th Fighter Squadron from Moody Air Force Base, Georgia, for example, deployed to Incirlik Air Base, Turkey, in October for missions against the Islamic State.

It's likely the battle over how the Air Force can phase out the Warthog will reemerge if members of Congress disagree with the FY17 plan.

"If there were any lingering doubts about the continued value and effectiveness of the A-10, one only need to look to Syria where the A-10 is taking the fight to ISIS, to Europe where the A-10 is assuring allies, or to the Korean peninsula where the A-10 is deterring aggression," Sen. Kelly Ayotte, R-N.H., said in October.

"When the Obama Administration submits its 2017 budget request in the coming weeks, I hope it will follow through on its plan to keep the A-10 flying so that it can continue to protect American troops, many still serving in harm's way," Sen. John McCain, R-Ariz, chairman of the Senate Armed Services Committee and a strong A-10 advocate, said after it was announced the A-10 would survive its "premature" retirement.

Officials are hoping the transition plan proposed in the new budget, however, "will allow us to maintain vital fighter capacity as we transition to the F-35 and deal with a resurgent Russia and a protracted counterterrorism war in Iraq, Afghanistan and Syria," Chief of Staff Gen. Mark Welsh said in a release on Friday.

The goal for the Air Force is to declare the F-35's initial operational capability between August and December 2016. Hill Air Force Base, Utah; Nellis Air Force Base, Nevada; and Luke Air Force Base, Arizona; are poised to receive the first F-35s in FY17.

"Replacing [the A-10] with F-35s on a squadron-by-squadron basis ... we'll always have enough aircraft for today's conflicts," Carter said on Feb. 2.

Oriana Pawlyk covers deployments, cyber, Guard/Reserve, uniforms, physical training, crime and operations in the Middle East, Europe and Pacific for Air Force Times. She was the Early Bird Brief editor in 2015. Email her at opawlyk@airforcetimes.com.