AUKUS is the trilateral security partnership announced on 15 September 2021 by Australia, the United Kingdom, and the United States. Its work is organised into two streams, commonly referred to as pillars, and the so-called "deep capabilities" architecture refers principally to Pillar II.
- Pillar I focuses on helping Australia acquire conventionally armed, nuclear-powered submarines. Under the Optimal Pathway announced in San Diego on 13 March 2023, Australia is expected to purchase Virginia-class submarines from the US in the early 2030s before transitioning to a new SSN-AUKUS class built in cooperation with the UK.
- Pillar II covers joint development and fielding of advanced capabilities. Publicly identified workstreams have included undersea capabilities, quantum technologies, artificial intelligence and autonomy, advanced cyber, hypersonic and counter-hypersonic systems, electronic warfare, innovation, and information sharing.
The "deep capabilities" label is often used informally by officials and analysts to emphasise that Pillar II is not a single programme but a portfolio of technology lines intended to deliver operational capability faster than traditional procurement cycles. Implementation relies on reforms to export-control regimes — notably US amendments to the International Traffic in Arms Regulations (ITAR) that took effect in 2024, creating a licence-free environment for most defence trade between the three partners, and corresponding changes to Australia's Defence Trade Controls Act.
Pillar II is structurally more open than Pillar I: officials in Washington, London and Canberra have publicly discussed potential project-by-project cooperation with additional partners. Japan was identified in an April 2024 trilateral defence ministers' statement as a candidate for consultation on specific Pillar II projects, though no formal membership exists. Canada, New Zealand and South Korea have also been mentioned in public discussion. The framework remains a partnership rather than a treaty-based alliance, and obligations flow through bilateral and trilateral implementing arrangements rather than a single chartering instrument.
Example
In April 2024, the AUKUS defence ministers announced they were consulting with Japan on cooperation under specific Pillar II projects, signalling the first potential expansion of the deep-capabilities track beyond the original three members.
Frequently asked questions
No. AUKUS is a trilateral security partnership, not a collective-defence treaty. It contains no mutual defence clause comparable to Article 5 of the North Atlantic Treaty.
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