MPs have voted in favour of renewing the UK's Trident nuclear weapons system.
The decisive result - by 472 votes to 117, majority 355 - 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 £10 billion 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 Theresa May, in her first despatch box appearance as Prime Minister, warn it would be a "reckless gamble" for the UK to rely on other nations for its nuclear deterrent. May also launched an attack on 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.
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.
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".
As the result was announced, some were relieved at the news.
#Trident vote goes the only way it could. We need to hold on to ultimate deterrent - to do otherwise would be to fail our country 472 v.117
-- Jeremy Snook (@jsprcouk) July 18, 2016
What kind of person is it that doesn't want to defend their freedom and way of life? #Trident
-- #GAWA ? (@Uunionist) July 18, 2016
The most sensible decision parliament has made in ages. Overwhelming yes to renew #Trident .
-- Nick (@CloudSurferUK) July 18, 2016
While others, although not surprised, wholly disagreed with the decision.
Shame on all of the MPs who've voted for renewal #Trident won't make us safer. Sad day for this country & for the global campaign for peace
-- Phélim Mac Cafferty (@Phelimmac) July 18, 2016
What a huge waste of public money to renew #Trident. Opportunity missed to lead in nuclear disarmament by example. Another sad day.
-- Julian Fitzsimons (@JulianFitzsimon) July 18, 2016