British lawmakers voted late Monday to back the renewal of Britain's submarine-based Trident nuclear missile system.
The vote of 472-117 came after Prime Minister Theresa May urged the House of Commons to act to to deter "serious threats."
"We cannot abandon our ultimate safeguard out of misplaced idealism. That would be a reckless gamble," May told parliament, which later passed the measure easily, despite opposition from the Scottish National Party and some Labour lawmakers.
"There is a continuing risk of further proliferation of nuclear weapons. We need to be prepared to deter threats to our lives."
May warned the 58 SNP lawmakers that their planned vote against Trident would put them "against jobs for Scotland."
Citing an estimated initial cost of 35 billion pounds (41 billion dollars) to replace four submarines over the next 35 years, she argued that continued possession of nuclear weapons was crucial to preserve Britain's global military reach.
"Abandoning our deterrent would not only undermine our own security but also that of our NATO allies," May said.
The GMB, one of Britain's largest trade unions, backed the call to renew Trident "to give stability and security to workers and industry."
The largest opposition party, Labour, supported the renewal of Trident, but Labour leader Jeremy Corbyn wants Britain to scrap its nuclear weapons, and he gave lawmakers a free vote on Monday.
"I do not believe the threat of mass murder is a good way of dealing with international relations," Corbyn told parliament.
In a YouGov survey of 1,631 people, 44 per cent of respondents agreed that Britain should renew the Trident system, while 22 per cent said it should be scrapped and 10 per cent said the submarines should be used without nuclear missiles.
Defence Secretary Michael Fallon said earlier Monday that Britain must keep nuclear weapons to "deter any kind of adversary, whether it's a country or a terrorist group."
"We can't be sure what threats will come against Britain in the 2040s and 2050s," Fallon told BBC Radio 4's Today programme, noting that not renewing the Trident system was "a gamble we simply can't afford to take."
"We need to be sure that [potential attackers] are always unsure as to how we might respond and if we might retaliate," he told the broadcaster.
The missiles are carried on four submarines based in Scotland. In a recent policy statement, the SNP said nuclear weapons were "immoral, ineffective and expensive."
"In times of imposed austerity, the 205 billion pounds which would be spent on a Trident replacement over the next 30 years could be far, far more effectively used on improving healthcare, childcare, education and building a better future for our children," the party said.