WASHINGTON — The U.S. Air Force is officially putting down its money to buy two different models of light-attack aircraft.

The service will purchase two to three aircraft each of the Textron Aviation AT-6 and Sierra Nevada Corporation/Embraer Defense & Security A-29 aircraft. The handful of planes will be used to support “allies and partner capacity, capability and interoperability via training and experimentation,” according to an Air Force announcement.

The A-29 Super Tucano contract should be awarded before the end of the year, with the AT-6 Wolverine contract coming in early 2020.

The plan to buy a handful of planes was previewed earlier this year by Air Force officials, but the companies will likely breathe a sigh of relief now that the deal is done. The purchase provides a much-needed show of confidence in the project. The two companies have invested internal funds on the Air Force’s light-attack experiment over the past two years and remain hopeful the service moves forward with a bigger buy of light-attack aircraft in the future.

The missions and basing for the planes will be different.

The AT-6s will go to Air Combat Command at Nellis Air Force Base, Nev., for “continued testing and development of operational tactics and standards for exportable, tactical networks that improve interoperability with international partners,” according to the Air Force announcement. The A-29s will go to Air Force Special Operations Command at Hurlburt Field, Fla., and will be used to “develop an instructor pilot program for the Combat Aviation Advisory mission, to meet increased partner nation requests for light attack assistance,” per the release.

“Our focus is on how a light attack aircraft can help our allies and partners as they confront violent extremism and conduct operations within their borders,” Air Force Chief of Staff Gen. David Goldfein said in the statement. “Continuing this experiment, using the authorities Congress has provided, gives us the opportunity to put a small number of aircraft through the paces and work with partner nations on ways in which smaller, affordable aircraft like these can support their air forces.”

Experiments will continue with a focus on creating a joint architecture and information sharing.

The Air Force has said that funding for the initial AT-6 and A-29 buys will come out of the estimated $160 million in unspent funds that Congress appropriated for the effort in previous budgets. Congress has appropriated $200 million in total for the effort since it was announced in late 2016.

Valerie Insinna contributed to this report.