In an interview with Defense News, Paolo Zampolli said he had been discussing the idea of the U.S. entering the tri-nation Global Combat Air Programme.
Five former defense chiefs are calling on Congress to hold immediate hearings on Trump's firings of the Joint Chiefs chairman and other senior leaders.
The U.S. is in a race to field the capability and develop systems to defend against hypersonic missiles, which China and Russia are developing and testing.
Experts say it's unlikely the Air Force could save $15 billion only targeting the kind of diversity and climate change programs Sec. Hegseth has derided.