The USA has assessed the proposed sale of 42 Lockheed Martin F-35A fighter aircraft to Japan at $10 billion.
In a notification to Congress, the US Defense Security Cooperation Agency outlined the details of the proposed Foreign Military Sales (FMS) deal. The package covers an initial four F-35s and an option to purchase 38 additional aircraft.
In December 2011, Japan selected the conventional take-off and landing variant of the F-35 as the winner of an F-X competition to replace its McDonnell Douglas/Mitsubishi Heavy Industries F-4 Phantoms. The F-35 defeated rival bids from the Boeing F/A-18E/F Super Hornet and Eurofighter Typhoon.
The FMS package includes the aircraft, Pratt & Whitney F135 engines - including five spares - electronic warfare systems and other equipment. It also includes logistical support, including software development and integration, spare parts, training and other elements.
© Lockheed Martin
At $10 billion, the deal values each aircraft at roughly $238 million, although this number includes a lifetime of support.
While Japan has long desired a stealth fighter - it mounted a long but ultimately futile quest to obtain the Lockheed F-22 - it warned in February that cost rises associated with the F-35 could result in it cancelling its planned order.
In an email to Flightglobal, the Japanese ministry of defence outlined Tokyo's current position on price increases. It said that if the cost increases "without valid reasons, there is a possibility that a procurement could be cancelled".
The email added: "This message is conveyed to the US side occasionally. [The] MoD will continue to request the US government to deliver the aircraft at the price, in accordance with the content of the proposal by the period requested."
Increasing costs within the F-35 programme have been a contentious issue among other future operators, including Australia, Canada and Norway.
Lockheed has said that the F-35A can be delivered for an average unit cost of about $75 million. However, that figure is based on an assumption that the USA and eight Joint Strike Fighter partner countries order more than 3,100 jets in the next 25 years.