Jeremy Corbyn has repeated belief he would never authorise the use of the UK’s nuclear weapons, amid deep Labour Party splits over Trident.
MPs are set to vote tonight on the renewal of the weapon system, which is estimated to cost around £40bn.
The Labour leader told the Commons today: “I make it clear today, I would not take a decision that kills millions of innocent people.”
He added: “I do not believe the threat of mass murder is a legitimate way to go about dealing with international relations.”
Corbyn will vote against Trident. But many of his MPs, including deputy leader Tom Watson and leadership candidate Owen Smith, will back renewal. Others MPs will abstain.
Theresa May told the Commons, in her first speech in parliament as prime minister, the nuclear deterrent was a “vital part of our national security and defence”.
And unlike Corbyn, she said she would authorise the use of Trident if she felt it necessary.
“Is she personally prepared to authorise a nuclear strike that could kill hundreds of thousands of innocent men, women and children?” May was asked.
The prime minister replied: “Yes.”
Corbyn famously caused a shadow cabinet row early in his leadership after he said he would never give the order to launch Trident.
As evidence of the Labour split, Watson told the BBC earlier this afternoon to “abstain is to not take responsibility” and that “security is the first duty of government”.
Labour’s deputy leader also predicted union workers would be “furious” with MPs, including Corbyn, who voted against Trident given the jobs that would be lost if it was scrapped.
Backbench Labour MPs heckled Corbyn with shouts of “is” when he said it was “was” party policy to back renewal.
John Woodcock told May that “whatever” Corbyn said, it remained Labour’s official policy to renew Trident.
Mike Gapes, the former Labour chairman of the foreign affairs committee, said it Trident was needed as it was a “dangerous time”.
And former shadow cabinet minster Caroline Flint told Corbyn “abandoning” the UK’s nuclear weapons would make it harder, not easier, to convince other nations to disarm.