The US Air Force has awarded Boeing a contract for two commercial 747-8 aircraft to replace an aging fleet of 747-200s serving as presidential transports.

The latest contract modifies an existing deal with Boeing awarded in 2016 to analyse options for reducing the risk of technical glitches in development of the new Air Force One fleet, as well assess classified requirements.

The USAF announced on 4 August did not disclose the price of the two aircraft, which Boeing previously built for delivery to defunct Russian airline Transaero.

More cost information will be released after a follow-on contract is awarded for Boeing to develop a preliminary design for the Air Force One modifications, according to a USAF statement.

“Because the aircraft were purchased through commercial contracting procedures, price and other related details are commercial-competition sensitive, meaning the negotiated price paid is not releasable,” the USAF states. “However, the price will be part of the overall programme cost baseline once it is set and will be released in accordance with the contract publication requirements.”

Following modifications, the presidential aircraft replacement will begin flying in 2024.

In January, Defense Secretary James Mattis ordered an immediate review of the Air Force One recapitalisation, following US president Donald Trump’s tweeted complaints that Boeing's cost proposals were too high.

In March, a series of requirements reviews outlined the minimum set of requirements for the platform, including incorporating a mission communications system, electrical power upgrades, a medical facility, an executive interior, a self-defence system and autonomous ground operations.