WASHINGTON — When the US Air Force first announced its plans to divest the A-10 Warthog in the fiscal 2015 budget, the service may not have had enough quality information to truly understand the impact of that decision, a new Government Accountability Office report contends.

According to a study released Aug. 24, the Air Force initially intended to retire the A-10 Warthog without having a full understanding of the capability gaps that could have resulted by mothballing the fleet. Although the service was aware of some of the risks, it did not establish clear requirements for all of the missions the aircraft performs — a fact the GAO believes could hamper future divestment decisions.

The Air Force is currently mulling the future of close-air support, including its plans for the Warthog fleet and the potential procurement of an A-X to replace it.

Spurred in part by ongoing operations against the Islamic State group that have taxed the fighter force, the service earlier in 2016 pushed the A-10 divestment to the right by three years, a plan that would see all planes mothballed by 2022. New Air Force Chief of Staff Gen. David Goldfein told lawmakers during his June confirmation hearing that he would support retaining the A-10 fleet in the near term.

But the GAO said that even the Air Force’s new plan incurs some level of risk because the service has still not yet fully analyzed potential capability gaps for all of the missions related to the A-10, which includes close-air support, combat search and rescue, and counter fast attack craft, among others. Without that information, it cannot ensure that all requirements are being met.

The service also has not determined whether training for other aircraft would change as a result of the A-10 divestment, it said.

The Air Force is trying to reduce the risk of retiring the Warthog by developing new weapons, establishing a close-air support integration group and making changes to the training of joint terminal attack controllers, the report acknowledged.

However, GAO believes the effectiveness of those efforts is unclear. The office pointed out that the Air Force continues to develop new methods to mitigate the divestment even as the first A-10s are slated to retire in 2018, which may suggest a haphazard plan.

"The Air Force’s ability to determine the effectiveness and necessity of its mitigation strategies is currently limited, because it does not have clear requirements for CAS and the other missions performed by the A-10, though it has recently begun examining them," GAO said.

That analysis is critical in terms of making sure the Air Force is effectively expending its resources.

"For example, an examination of CAS requirements could shed light on the relative importance of the capability to destroy moving and armored targets, something the A-10 does well," the GAO said. "Should DOD determine that it is not an important capability, the Air Force could focus its limited resources on developing higher priority capabilities."

The service, in a June 21 statement signed by Air Force Secretary Deborah Lee James, rebutted all of GAO’s recommendations.

The Air Force conducted multiple analyses that evaluated the effects of divesting various platforms, the service’s response said. That analysis "indicated the A-10 divestment was the most acceptable strategy to remain within the Air Force budget authority while controlling risk across all Air Force mission sets."

The service has also issued a report to Congress that details the A-10's close-air support capabilities in comparison to other platforms that perform the mission.

"Therefore the Air Force takes exception to the assertion that it made the decision to divest the A-10 without knowledge and understanding of the associated risk and capability gaps," the service said in its response.

No additional information-gathering practices are needed in order to give senior leaders a complete picture of the effects of a potential divestment, it added.

One way the Air Force could more fully understand its close-air support requirement is to work more closely with the Army, suggested Dan Grazier, a fellow at the nonprofit Project on Government Oversight.

"The Air Force needs to sit down with the Army and they need to hash out exactly how close-air support needs to be performed," he said.  "What is close-air support? What’s the Army’s concept of close-air support? How are they going to perform the mission? Then they design an aircraft around that."

Going forward, the GAO report could give ammunition to congressional A-10 advocates who have fought against the aircraft’s divestment.

"Today’s report confirms what I’ve argued continuously — the Air Force’s flawed and shifting plan to prematurely retire the A-10 is dangerous and would put lives in danger," said former A-10 pilot Rep. Martha McSally, R-Ariz. "According to GAO, the Air Force has no replacement to perform Combat Search and Rescue or Forward Air Control (Airborne) missions. There’s no replacement for the A-10’s unique ability to carry out Close Air Support, including situations that require an ability to loiter, fly under weather, and visually identify friendly and enemy forces."

Retiring the A-10 before fielding its replacement could leave the Air Force with a "serious" capability gap, according to Senate Armed Services Committee Chairman John McCain, R-Ariz.

"At a time of growing threats to our national security, any divestment of this critical aircraft without the fielding of a suitable replacement would leave our men and women in uniform without the best close air support weapon in our arsenal that is needed now more than ever to meet the challenges of a more dangerous world," he said in a statement applauding the GAO report.