The construction of the UK nuclear deterrent programe's latest submarine has begun, marking a significant milestone.
In a ceremony at BAE Systems' Barrow-in-Furness site, the steel was cut on Warspite, the third of four new submarines.
The new Dreadnought class is made up of four new ballistic nuclear subs - Dreadnought, Valiant, Warspite and King George VI.
Weighing more than 17,000 tonnes and measuring 153 metres, they will be tasked with patrolling at sea 365 days a year, carrying Britain's Trident missiles.
The submarines will also contain 26.4 miles of pipework and more than 215 miles of cables.
Alex Chalk, Defence Procurement Minister, said "progress on the Dreadnought Class is crucial to maintaining our national security".
"Our nuclear deterrent protects every UK citizen from the most extreme threats, every minute of every day," he said.
"This milestone is a significant step forward in the Dreadnought programme, supporting thousands of jobs and apprenticeships across the country, and protecting the UK and our allies for decades to come."
Work is set to continue on Warspite, as well as the first two boats Dreadnought and Valiant, incorporating some of the most advanced systems and world-leading technology.
Rear Admiral Donald Doull, Senior Responsible Officer, Dreadnought, said the steel cutting is "an important step" in the delivery of Dreadnought programme.
"It is a key milestone for the programme's mission to replace the current Vanguard Class submarines with four Dreadnought Class submarines, enabling their successful entry into service," he said.
"Successful delivery of the Dreadnought Programme is a challenge that will take the determined effort of everybody with a responsibility for supporting the Programme – getting to this milestone is a huge achievement, which reflects the personal and collective commitment of all concerned."
The submarines will start to enter service from the early 2030s, with the construction of Dreadnought supporting tens of thousands of jobs across the UK.