Australia’s new defence secretary has claimed buying only second-hand submarines from the United States was always the preference for AUKUS, before later clarifying to a Senate committee that the project could have “two constrained optimal pathways”.

During her first public appearance since taking over the high-powered role, Meghan Quinn was grilled by senators about recently announced changes to the $368 billion project to acquire a nuclear-powered fleet to replace the ageing Collins-class boats.

Over the weekend, the defence minister confirmed Australia would now receive three “in service” Virginia-class submarines from the US, instead of one new and two second-hand boats, arguing the move would improve simplicity and be significantly cheaper.

Under questioning from shadow defence minister James Paterson at a Senate Estimates hearing on Tuesday night, the newly appointed defence boss initially gave evidence that the recently adjusted approach to AUKUS had always been Australia’s preferred plan.

The Secretary was asked which country had made the decision that only “in service” boats would now be purchased from the United States, instead of Australia receiving one new submarine and two “in-service” boats.

“Australia’s position is that we would always have a preference for three in-service (submarines),” Ms Quinn responded.

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