(CNN) The US Air Force announced Friday that it has finalized a deal to purchase two already-built aircraft from Boeing to serve as the next generation of Air Force One, flying future presidents around the world for decades to come.

A Boeing spokesperson told CNN the two aircraft in question were originally destined for a now bankrupt Russian airline.

"The Air Force awarded a contract modification to Boeing on Aug. 4, 2017, to purchase two commercial 747-8 aircraft for future modification to replace the two aging VC-25A Presidential support aircraft," Air Force spokesperson Ann Stefanek said in a statement, using the military's official name for the Air Force One 747 aircraft.

President Donald Trump had been fiercely critical of the cost of the new Air Force One program, stating "costs are out of control" and "cancel order!" in a December tweet. The new planes would replace the current VC-25 aircraft, which entered service in 1990.

CNN had previously reported that the Air Force was examining the option of purchasing pre-existing planes in order to keep costs down.

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