Dreadnought submarines to take Royal Navy's nuclear deterrent into the 2070s

New Dreadnought-class submarines are set to replace the ageing Vanguard fleet as the future of the UK's Continuous At Sea Deterrent (CASD).

The Royal Navy has maintained an unbroken at-sea deterrent patrol for more than half a century, but the submarines that currently carry the UK's nuclear warheads are nearing the end of their service lives.

The Dreadnought-class will take over that role.

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At more than 150 metres long, the new submarines will carry the Trident II D5 ballistic missiles, continuing the UK's nuclear mission that began in the 1960s.

Each vessel will have a displacement of 17,000 tonnes and will be fitted with X-rudders, designed to reduce noise underwater.

They're also expected to remain in service for 35 to 40 years – significantly longer than their predecessors.

But despite the urgency, the first of the four Dreadnought submarines isn't expected to enter service until the 2030s.

The Vanguard class first entered service in the 1990s, with a planned service life of around 25 years. That timeline has long passed, yet all four boats remain in service. HMS Vanguard itself was originally due to retire in 2024.

Construction of the new class is taking place at Barrow-in-Furness in Cumbria, with the first steel cut for HMS Dreadnought back in 2016 – just two years before HMS Vanguard was due for retirement.

The total cost of the project is £41bn, which includes £31bn – adjusted for inflation – for development and production, and a further £10bn set aside for contingencies.

There is also now a need for further investment in shore-based infrastructure, including upgrades at HM Naval Base Clyde (Faslane), to accommodate the larger submarines.

It's a considerable financial commitment at a time when defence budgets are under pressure. The government has pledged to increase defence spending to 2.5% of GDP by 2027 – a move that could ease some of the strain.

But much of that additional spending is already being pulled towards supporting Ukraine in its land war against Russia.

With Russia and China both continuing to invest heavily in their own conventional and nuclear forces – and with growing threats to undersea infrastructure and more frequent incursions by Russian naval vessels near UK waters – questions remain.

Can the Royal Navy afford not to invest in its continuous at-sea deterrent?

The Dreadnought-class will replace a fleet already beyond its expected life, securing the UK's strategic deterrent into the 2070s – a capability that has underpinned the country's defence strategy for decades.