Speaking on the sidelines of the Singapore Airshow, Tim Cahill, Lockheed Martin’s senior vice-president for Global Business, confirmed Thailand had expressed interest but said there was “nothing official that I am aware of that has come relative to that”.

In January, the Southeast Asian country’s air force set aside about US$413 million for procuring four of the jets. Earlier, Air Chief Marshal Napadej Dhupatemiya said Thailand would be interested in buying as many as eight F-35s.

“This will be a US government policy decision,” Cahill said. “I think there is some promise there, but I honestly don’t know where the US government will come down on that.”

A US State Department spokesperson said it does not confirm or comment on proposed defence transfers or sales until they have been formally notified to Congress.

The F-35, one of the world’s most advanced fighter aircraft, is considered a highly sensitive export, sold only to the US’ closest allies. In the Indo-Pacific region, only Australia, Japan, South Korea and Singapore fly the jet.