UK SDR 2025: UK outlines plan to build up to 12 SSN-AUKUS submarines

The UK has confirmed plans to build up to 12 new SSN-AUKUS submarines as part of the 2025 Strategic Defence Review. (BAE Systems)

The UK government has laid out ambitions to significantly expand the Royal Navy's (RN's) nuclear-powered attack submarine (SSN) fleet as part of its 2025 Strategic Defence Review (SDR).

Announced by UK Prime Minister Sir Keir Starmer on 2 June, the review confirms an intention to build up to 12 next-generation SSN-AUKUS boats to succeed the RN's seven Astute-class SSNs from the late 2030s.

Plans to equip the UK and eventually Australia with a future SSN known as SSN-AUKUS were first unveiled by Australia, the UK, and the US in March 2023 under the trilateral AUKUS security partnership arrangement. The new submarine builds on the UK's SSN replacement SSN(R) design, but will additionally incorporate technology inputs from all three AUKUS partners, including US-developed technology such as propulsion plant systems, a common vertical launch system, and weapons.

Construction of the new boats is set to begin towards the end of the decade, with the first SSN-AUKUS submarine planned to enter service with the RN around 2038. According to the UK Ministry of Defence (MoD), delivery of SSN-AUKUS will see a major expansion of industrial capability at BAE Systems' Barrow-in-Furness shipyard and Rolls-Royce's nuclear reactor production facility in Raynesway (Derby), with the intention to achieve a production ‘drumbeat' of one new submarine every 18 months.

“The increase in capacity at the two sites will allow the UK to increase its fleet to up to 12 attack boats as part of the AUKUS partnership,” the MoD said.