AUKUS Pillar 1

AUKUS Pillar 1 is the nuclear-powered submarine acquisition component of the AUKUS trilateral security partnership, announced on September 15, 2021. Pillar 1 represents the largest defense acquisition in Australian history and fundamentally transforms Australia's submarine capability from diesel-electric (Collins-class) to nuclear-powered attack submarines (SSNs).

The 'Optimal Pathway' announced on March 13, 2023, by the leaders of Australia, the UK, and the US, consists of three phases:

Phase 1: Submarine Rotational Force-West (SRF-West) — from ~2027 Beginning around the end of 2027, US and UK nuclear-powered submarines will rotate through HMAS Stirling in Western Australia. The SRF-West will include one UK Astute-class SSN and up to four US Virginia-class SSNs at any given time. Australia has committed AUD 8 billion for HMAS Stirling infrastructure upgrades to support these rotations, including wharf facilities, maintenance support, and crew accommodation. This phase provides immediate capability enhancement and builds Australian experience with nuclear submarine operations.

Phase 2: Virginia-class acquisition — 2032/2035/2038 The United States will sell Australia three Block IV Virginia-class SSNs, with delivery sequencing around 2032, 2035, and 2038 (revised May 2026). Australia will become only the second country (after the UK) to operate US nuclear submarines. The Virginia-class provides advanced SSN capability including stealth, sensors, weapons, and endurance. The acquisition includes training, maintenance infrastructure, and nuclear regulatory framework development. A potential option for up to two additional Virginia-class submarines exists if the SSN-AUKUS program experiences delays.

Phase 3: SSN-AUKUS — from early 2040s A new trilateral submarine design (SSN-AUKUS) will be built by the UK and Australia, with the first boats entering service in the early 2040s. SSN-AUKUS will be based on the UK's next-generation SSN(R) design, incorporating Australian requirements and US technology. The UK will build the first SSN-AUKUS, with Australia building subsequent boats at Osborne Naval Shipyard in South Australia. The SSN-AUKUS will use the Rolls-Royce PWR3 nuclear reactor.

Key aspects of Pillar 1:

• Nuclear regulatory framework: Australia has enacted the Australian Naval Nuclear Power Safety Bill to establish a regulatory framework for nuclear submarine operations. ANSTO will play a key role in nuclear stewardship.
• Workforce development: Australia needs to train thousands of personnel in nuclear submarine operations, maintenance, and regulation. This includes naval crews, shipyard workers, and regulatory staff.
• Industrial base: Osborne Naval Shipyard in South Australia is being expanded for SSN-AUKUS construction. The UK's Barrow-in-Furness shipyard will build the first SSN-AUKUS.
• US industrial base: The Virginia-class acquisition depends on US submarine industrial base capacity, which has been stretched by US Navy requirements. The US has committed to increasing submarine production to support both US and Australian needs.

Pillar 1 represents a generational investment in Australian defense capability. The total cost is estimated at AUD 268-368 billion over the program lifetime, making it the largest single defense acquisition in Australian history. The program transforms Australia's strategic posture by providing a sovereign SSN capability that can project power throughout the Indo-Pacific and contribute to allied deterrence.