Why was France outside AUKUS, and would a French test-bed submarine have helped the cancelled Australian programme?
Short answerA demonstrator could have reduced technical risk, but AUKUS rests on unusually close technology and foreign-policy alignment among Britain, the United States, and Australia.
NotesA French-built demonstrator might have reduced risk by proving the conversion from a nuclear attack-submarine design to a conventional boat. That cancelled commercial programme is separate from the strategic logic of AUKUS. Britain, the United States, and Australia already share intelligence, technology, and a strong tendency toward operational support, while France more often preserves freedom for an independent foreign policy. For an integrated engineering programme, dependable access to components and common policy in a crisis can matter as much as the technical merits of a competing design.