UK begins SSN AUKUS nuclear submarine production to support US and Australia across Indo-Pacific.

On June 25, 2025, Babcock confirmed the commencement of long-lead work on the SSN-AUKUS nuclear-powered attack submarine program, marking one of the initial UK industrial contributions to the trilateral initiative involving the United Kingdom, Australia, and the United States. The announcement was included in Babcock’s preliminary results for the financial year ending 31 March 2025. The company’s Mission Systems division secured two contracts in FY25, one of which enables it to begin procurement for the first components of the weapon handling and launch system intended for the Astute-class replacement. Babcock’s participation in the SSN-AUKUS program aligns with its broader involvement in submarine systems, including past contributions to the Astute and Dreadnought classes, as well as the manufacture of missile tube assemblies for the UK and US deterrent fleets.
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Each SSN-AUKUS submarine is projected to displace over 10,000 tonnes, feature a turbo-electric propulsion system powered by Rolls-Royce’s PWR3 reactor, and include X-form control surfaces for improved maneuverability. (Picture source: British MoD)

The SSN-AUKUS submarine is intended to replace the UK’s Astute-class submarines from the late 2030s and to form the foundation for Australia’s first fleet of conventionally armed, nuclear-powered attack submarines. The program is part of AUKUS Pillar 1 and is based on the UK’s SSN(R) concept, which evolved from the Maritime Underwater Future Capability (MUFC) initiative launched in 2018. Following delays in the Astute and Dreadnought programs, SSN(R) was renamed SSN-AUKUS in March 2023 when Australia joined the program. As part of this evolution, the UK and Australia are jointly developing the class with the incorporation of US technologies. These include propulsion systems, vertical launch systems, and a shared combat system based on the AN/BYG-1, enhancing interoperability across all three navies. The UK plans to build up to 12 units, while Australia intends to construct five SSN-AUKUS submarines at the Osborne Naval Shipyard in South Australia and also acquire up to five Virginia-class boats from the United States.

The design of the SSN-AUKUS submarine is based on the concept developed for SSN(R). It is projected to displace over 10,000 tonnes, feature a turbo-electric propulsion system powered by Rolls-Royce’s PWR3 reactor, and include X-form control surfaces for improved maneuverability. Other features likely to be incorporated include a shrouded propulsor for reduced acoustic signature, hull-mounted hydroplanes, and optronic masts instead of traditional periscopes. The armament layout is expected to include six 21-inch torpedo tubes for torpedoes, mines, or unmanned underwater vehicles, along with three modular payload bays housing seven vertical launch tubes each, enabling the deployment of land-attack cruise missiles and future payloads. Sensor systems are anticipated to consist of bow sonar, flank arrays, and fin-mounted sensors for comprehensive underwater detection coverage. These specifications are derived from public concept illustrations and analysis rather than official technical documentation.

Construction of the first UK SSN-AUKUS submarine is scheduled to begin at BAE Systems’ Barrow-in-Furness shipyard in the late 2020s, with entry into service anticipated in the late 2030s. Australia is expected to begin production of its first unit by the end of this decade, aiming for delivery in the early 2040s. Reactor production will occur at Rolls-Royce’s Raynesway facility in Derby, which is being expanded with investment from both the UK and Australia. The Australian government has committed £2.4 billion over ten years to support the expansion of this facility, in addition to financing its domestic construction yard. A trilateral workforce integration initiative is already underway, with Australian personnel embedded within UK and US submarine programs. The program’s overall workforce impact is projected to include 30,000 UK-based jobs, 30,000 apprenticeships, and 14,000 graduate roles over the next decade. The goal is to deliver one submarine every 18 months once full-rate production begins in the 2030s. A production green light is expected in 2028, following the completion of the five-year Detailed Design and Long Leads (D2L2) phase.

The UK Government’s Strategic Defence Review (SDR), published in 2025, announced increased defence spending, targeting 2.6% of GDP by 2027, with the potential to rise to 3% in the next parliamentary term. This includes £6 billion allocated to nuclear submarine production and £4.5 billion to munitions, as well as a broader national security expenditure goal of 5% of GDP by 2035. The SDR emphasized the role of defence in economic growth and the need for greater industrial cooperation. The review also included commitments to expanding facilities at HMNB Clyde in Scotland, with an initial investment of £250 million. The SSN-AUKUS initiative is expected to support long-term UK strategic objectives, including the enhancement of submarine readiness and reinforcement of the submarine industrial base. Additional Australian involvement includes the establishment of the H&B Defence joint venture between Babcock and HII, which in May 2025 secured its first contract to lead a two-year supplier qualification program in Australia, focusing on integrating Australian firms into the Virginia-class supply chain.

The SSN-AUKUS program is developing against a backdrop of structural challenges experienced during the Astute-class submarine program. Only five Astute-class submarines are currently commissioned, with two still under construction. Delays in infrastructure availability, particularly at Devonport and Faslane, have limited the deployability of these vessels. HMS Ambush and HMS Artful have not undertaken operations for nearly three years, and HMS Audacious remained idle for 18 months awaiting dry dock access. The new submarine class is expected to address design issues that hindered maintainability and upgrade potential in the Astute boats. The UK is investing in port infrastructure, including Project EUSTON, to acquire floating dry docks and ease congestion at existing maintenance sites. The submarine availability rate is projected to improve if the new class is successfully delivered and maintained at regular intervals. However, scaling up workforce recruitment remains a challenge due to the unique operational demands placed on submariners and the competition with civilian employment opportunities.

US involvement includes the transfer of three Virginia-class submarines to Australia starting in the early 2030s, with the possibility of two more. The Submarine Rotational Force – West, based at HMAS Stirling, will include one UK Astute-class and up to four US Virginia-class submarines on rotation beginning in 2027. Australia’s non-nuclear weapons status under IAEA safeguards restricts it from producing nuclear fuel, so reactor units for its SSN-AUKUS submarines will be manufactured and sealed in the UK. A UK-US bilateral status of forces agreement was signed in 2024 to facilitate Royal Navy participation in the rotation. In the US, concerns have been raised regarding the industrial capacity to supply both the US Navy's needs and Australian procurement. A Pentagon review initiated in 2025 reflects these concerns, including calls for Australia to increase defence spending from 2% to 3.5% of GDP. Political commentary in Australia has noted potential delays or reductions in US submarine deliveries, emphasizing the need for Australia to plan for contingencies should the Virginia-class deliveries not occur as scheduled.

As of mid-2025, the SSN-AUKUS program remains a trilateral initiative, with design responsibilities and technology sharing distributed across all three nations. While the number of submarines to be built by the UK has not been formally capped, the target remains up to 12. Cost estimates for individual units have not been released, but the total program cost is expected to exceed $40 billion. The program overlaps with the UK’s Dreadnought-class SSBN build, which continues into the 2030s. The UK’s Defence Nuclear Enterprise includes both programs and is receiving additional funding to expand capacity. Australian investment in the UK industrial base aims to alleviate pressure on UK and US supply chains and will support the development of critical components such as pressure hull steel, valves, batteries, and electrical systems. Australian industrial participation is also intended to help prepare its domestic sector for full-scale submarine production. The Nuclear Skills Taskforce, established in 2023, coordinates workforce development and academic collaboration to address personnel shortages in the nuclear defence sector.

If implemented on schedule, the SSN-AUKUS submarines will perform roles in intelligence, surveillance, anti-submarine and anti-ship warfare, and precision strike. The submarines are expected to offer capabilities for penetrating anti-access/area-denial zones, conducting long-range patrols, deploying unmanned underwater vehicles, and supporting special operations. The class is intended to remain in service for multiple decades and represents a significant part of the UK and Australia’s long-term naval posture. The initiative also contributes to the US strategic presence in the Indo-Pacific region and includes rotational basing access for allied submarines. Challenges remain across industrial capacity, cost control, personnel retention, and infrastructure readiness, but the SSN-AUKUS program constitutes the core of the AUKUS Pillar 1 submarine cooperation plan and is central to the participating nations’ defence planning in the 2030s and beyond.