Britain's controversial Trident nuclear weapons system has been given a strong vote of confidence by MPs after they backed renewing the deterrent.
The decisive result - by 472 votes to 117 - was returned in support of a government motion which also included backing the plan to replace the existing submarine fleet carrying the missiles with four new Successor submarines.
Renewal of the continuous-at-sea deterrent is predicted to cost £31 billion, with a £10bn contingency fund also set aside.
Labour MPs were subject to a free vote, with leader Jeremy Corbyn declaring he would oppose the motion - a stance which led to strong criticism from some of his backbenchers.
The SNP, the third largest party in the Commons with 54 MPs, also opposed the Government's plan.
A debate lasting almost six hours saw new Prime Minister Theresa May warn it would be a "reckless gamble" for the UK to rely on other nations for its nuclear deterrent.
She insisted it would be an "act of gross irresponsibility" should the government discard the Trident weapons system, as she led calls to replace the submarine fleet which carries the missiles.
Mrs May also launched an attack on Jeremy Corbyn by claiming some opposition frontbenchers appeared to be the first to "defend the country's enemies" and the last to accept what the UK needs to protect itself.
In his remarks, Mr Corbyn questioned if the "weapons of mass destruction" act as a credible deterrent to the threats faced by the UK.
He also warned the costs of renewal were "ballooning ever upwards" and noted that each warhead has the capacity to kill one million people.
Mr Corbyn added he would not take a decision that "kills millions of innocent people" - a nod to his stance that he would not authorise the use of nuclear weapons.
The Labour leader and key allies, including shadow chancellor John McDonnell, were set to vote against the government motion.
But Labour MP Toby Perkins, who last month resigned as shadow armed forces minister, compared Labour frontbench opposition to Trident with the arguments "of a 13-year-old".
Jamie Reed, Labour MP for Copeland, launched a blistering attack on his leadership's position and warned it could split the party.
He branded Mr Corbyn's opposition "juvenile" and "narcissistic" and said shadow cabinet members who voted against Trident should resign and return to the backbenches because they would be voting against Labour Party policy.
Mr Reed said: "I urge all colleagues on the Labour frontbench tonight to respect the democratic processes of the Labour Party, to respect the conference decision of the Labour Party, to vote with the established policy of the Labour Party.
"And if you can't do that, return to the backbenches."
Angus Robertson, the SNP's Westminster leader, warned that renewing Trident would speed up independence for Scotland.
58 of Scotland's 59 MPs voted against Trident renewal - with Scotland's only Tory MP, David Mundell, being the sole supporter.
Mr Robertson was applauded and cheered by his colleagues in the Commons after his speech, in which he labelled Trident as an "immoral, obscene and redundant weapons system".
Mr Robertson said: "If Scotland is a nation, and Scotland is a nation, it is not a normal situation for the state to totally disregard the wishes of the people, and this government has a democratic deficit in Scotland, and with today's vote on Trident it's going to get worse, not better.
"It will be for the Scottish people to determine whether we are properly protected in Europe and better represented by a government that we actually elect - at this rate, that day is fast approaching."