The UK has secured a £10bn deal to supply the Norwegian navy with at least five new warships.
The agreement to provide Type 26 frigates will be the UK's "biggest ever warship export deal by value", the Ministry of Defence (MoD) said, while Norway said it would be its largest "defence capability investment" to date.
The government said the deal would support 4,000 UK jobs "well into the 2030s", including more than 2,000 at BAE Systems' Glasgow shipyards where the frigates will be built.
UK Prime Minister Sir Keir Starmer said the agreement would "drive growth and protect national security for working people".
"This success is testament to the thousands of people across the country who are not just delivering this next generation capabilities for our Armed Forces but also national security for the UK, our Norwegian partners and Nato for years to come," he added.
The deal is also expected to support more than 400 British businesses, including 103 in Scotland, the MoD said.
The agreement represents a victory for the British government and defence industry over France, Germany and the United States - which were also being considered by Norway as possible vendors.
It will create a combined UK-Norwegian fleet of 13 anti-submarine frigates - eight British and five Norwegian vessels - to operate jointly in northern Europe, significantly strengthening Nato's northern flank.
The warships will be constructed at the BAE systems yard in the Govan area of Glasgow, where frigates for the Royal Navy are currently being built.
Scottish Secretary Ian Murray said the choice of the UK "demonstrates the tremendous success of our shipbuilding industry and showcases the world-class skills and expertise of our workforce on the Clyde".
Norway's Prime Minister Jonas Gahr Støre, who informed Sir Keir of the decision to select the UK in a phone call on Saturday night, said the partnership "represents a historic strengthening of the defence cooperation between our two countries".
Støre said the government had weighed two questions in its decision: "Who is our most strategic partner? And who has delivered the best frigates?... The answer to both is the United Kingdom."
The Type 26 frigates purchased by the Royal Norwegian Navy will be as similar as possible to those used by their British counterparts, and have the same technical specifications.
They are specifically designed to detect and track enemy submarines and engage them in combat if necessary, with deliveries expected to begin in 2030.
UK Defence Secretary John Healey said the UK would "train, operate, deter, and – if necessary – fight together" under the defence deal.
"Our navies will work as one, leading the way in Nato, with this deal putting more world-class warships in the North Atlantic to hunt Russian submarines, protect our critical infrastructure, and keep both our nations secure," he added.
Eight Type 26 frigates are currently being built at BAE Systems' Glasgow shipyards for the Royal Navy, to replace its ageing Type 23 frigates.
Two of the warships, HMS Glasgow and HMS Cardiff, have been built and another three, HMS Belfast, HMS Birmingham and HMS Sheffield, are under construction.
BAE has also licensed the Type 26 design to Canada and is building the warships in Australia under contract.
As part of a £300m modernisation at BAE Systems, a new shipbuilding hall - dubbed the "frigate factory" - was opened earlier this year.
The Janet Harvey Hall, named after a pioneering female electrician, is large enough for two frigates to be built simultaneously.
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