The UK Ministry of Defence (MoD) have revealed plans to invest £15bn ($20.25bn) in its continuous at sea nuclear deterrent, and separately, the government pledge to expand its conventionally armed, nuclear-powered submarine (SSN) fleet under the trilateral AUKUS alliance.
This announcement comes just before the government unveils its long-awaited Strategic Defence Review (SDR) later today (2 June), wherein the government determines its Plan for Change to confront the global security crisis that will define the coming years.
Uniquely, the SDR is an externally-led review, albeit limited to the funding constraints set by the MoD. The new Labour government initiated the SDR when the Party was elected with a considerable mandate in July 2024. The report is expected to recommend the UK Armed Forces increase its readiness to deter growing threats – the document makes 62 recommendations which the government is expected to accept in full.
Britain will now strengthen its strategic capabilities beneath the surface. The Royal Navy has confronted the reality of Russia’s adverse activities underwater in the past several months which constitute measures in the so-called gray-zone, a dubious space between peace and war.
In April 2025, The Times discovered that Russian undersea sensors which were intended to spy on Britain’s nuclear-powered submarine fleet had washed up on UK shores.
Sovereign nuclear warheads
Britain, unlike other nuclear powers, projects its nuclear deterrent exclusively from nuclear-powered, ballistic missile submarines (SSBNs) at sea. The nation has at least one SSBN on continuous deployment at any one time as part of what is referred to as its continuous at sea deterrence.
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By GlobalDataAt present, the UK is developing its future SSBN fleet, known as the Dreadnought-class, which will replace the Navy’s four legacy Vanguard-class boats – they carry 12 and 16 missiles respectively.
The fleet is armed with a three-stage, solid-propellant, inertial-guided, strategic-level Trident 2 D5 nuclear ballistic missiles. Notably, the missiles are manufactured in the United States and are leased from a shared pool. The missiles are subsequently fitted with UK-made warheads – the section of the missile that contains the destructive agent.
Now, the SDR will see £15bn investment in the UK’s sovereign nuclear warhead programme.
This will see significant modernisation of infrastructure at the Atomic Weapons Establishment in Aldermaston, supporting more than 9,000 jobs at the Berkshire site.
Up to 12 SSN-AUKUS boats
During the Undersea Defence Technology conference in March, Rear Admiral Oliver Berdal, a Royal Norwegian Navy commander, asserted “it’s going to be hard to find [and detect] submarines for many more decades, and I think that’s also one of the reasons why the UK, the US, France, Russia, China, Israel, and many other nations are investing heavily in submarines.”
According to GlobalData intelligence, the global submarine market, valued at more than $40bn in 2025, is projected to grow at a compound annual growth rate of 5.1% over the next ten years.
GlobalData anticipates the SSBN segment to make up 34.3% share, followed by SSNs, which make up a 43.2% share.
In reference to the US-China rivalry, Berdal added that while the quality of experience and weapons within the US Navy remains superior, and “even though quality is important, quantity is a quality of its own.”
The UK appears to subscribe to this rationale with its pledge to build up to 12 more SSN-AUKUS boats. This is a considerable force expansion given the Royal Navy currently operate just five Astute-class SSNs, with two more in development. The 12 SSN-AUKUS are set to replace these units into the 2030s.
The boost to the SSN-AUKUS programme will see a major expansion of industrial capability at Barrow and Raynesway, Derby, with the build of a new submarine every 18 months.
This production timeline is ambitious given the enduring capacity and skills deficit that reverberates across the Western defence industrial base, particularly in the US. Currently, major American shipyards are struggling to reach a production rate of two Virginia-class SSNs per year.
If UK industry is going to be successful in delivering the objectives laid out in the SDR, then the MoD will need to do more to support contractors in expanding their infrastructure.
