Rishi Sunak has agreed a multi-billion-pound submarine deal with the US and Australia amid a growing international threat from China.
Mr Sunak said the three countries will work together “keeping our oceans free, open, and prosperous” with a new generation of nuclear-powered attack submarines.
The Prime Minister said the AUKUS partnership – a trilateral security pact between the three nations – would deliver “one of the most advanced” submarines ever, and create thousands of jobs in British shipyards.
Under the plan, the new SSN-AUKUS subs will be operational for the Royal Navy by the late 2030s, and will also give Australia its first nuclear-powered capability as it seeks to counter Chinese activities in the Pacific.
The vessels will replace the UK’s seven Astute-class subs, and though it hasn’t been confirmed how many will be ordered, the size of the hunter-killer fleet could double in size, according to Royal Navy insiders.
Mr Sunak met with US President Joe Biden and Australian Prime Minister Anthony Albanese in San Diego, California to finalise the defence pact and appeared at a joint press conference.
The PM said the three countries had agreed “the most significant multilateral defence partnership in generations”.
“Aukus matches our enduring commitment to freedom and democracy with the most advanced military, scientific, and technological capability,” he said.
“For the first time ever, it will mean three fleets of submarines working together across both the Atlantic and Pacific, keeping our oceans free, open, and prosperous for decades to come.”
He said the UK, US and Australia were “three allies who have stood shoulder to shoulder together for more than a century”.
He added: “Three peoples who have shed blood together in defence of our shared values.
The £5 billion extra for the military over two years announced the PM announced earlier on Monday will partly help develop the next phase of the AUKUS programme.
“And three democracies that are coming together again to fulfil that higher purpose of maintaining freedom, peace, and security now and for generations to come.”
The AUKUS programme will see closer collaboration between the three countries
Australia will purchase US Virginia-class subs in the 2030s as a short-term stop-gap until the new boats are operational as part of the agreement.
The three countries insisted that the agreement did not raise the risk of nuclear proliferation.
The submarines will carry conventional weapons and the nuclear reactors onboard will be sealed shut.
During the visit, Mr Biden said he intends to visit Northern Ireland to mark the 25th anniversary of the Good Friday Agreement, after being invited by Mr Sunak.
By Chris Samuel@chrisjesamuel