ABSTRACT On 15 September 2021, Australia signed onto a new security agreement with the US and UK known as AUKUS. Under AUKUS, Australia will acquire nuclear capabilities in the form of nuclear-powered submarines. Despite being the most significant security agreement since ANZUS with an estimated cost of over $368 billion it has been highly controversial. Concerns have been raised around its viability, practicality, the associated risks given the revival of isolationist foreign policy ideas in the US, and the financial costs and fit with existing domestic capabilities. What explains Australia’s decision to join AUKUS given the presence of such substantial risks and unknowns? I work to show that traditional security frameworks struggle to account for the significant risks associated with the decision. Instead, using an ontological security approach, I argue that Australia’s decision to enter AUKUS represents an effort to maintain ‘Self’ identity narratives through the stabilisation of relations with ‘great and powerful friends’ that had come into question under the Trump presidency.