The centrepiece of the AUKUS defence pact agreed between Australia, the United Kingdom, and the United States in September 2021 was a commitment to help Australia acquire nuclear-powered submarines. This made redundant an earlier $90 billion deal Australia had entered into with France to deliver conventionally powered submarines. Australiaâ€™s decision to renege on the French deal, as well as the revelation that three of Franceâ€™s key partners had negotiated AUKUS in secret, triggered a furious French diplomatic response. In this commentary, we explore the ramifications of this episode for future Australia-France relations. We begin by documenting the immediate diplomatic fallout of the AUKUS announcement and tracing how the dispute became personalised between Australian Prime Minister Scott Morrison and French President Emmanuel Macron. We then move to consider how the episode reveals the divergent approaches Australia and France are taking in response to Chinaâ€™s growing influence in the Indo-Pacific. Finally, we highlight three reasons why this episode represents a theoretically valuable case study for scholars interested in the roles of trust and leadership in global politics, given it features the breakdown of interpersonal trust between leaders of friendly states.