Theresa May warns threat of nuclear attack has increased ahead of Trident vote

Theresa May will warn it would be a “gross irresponsibility” for the UK to surrender its independent nuclear deterrent, when she opens the debate on Trident renewal in the House of Commons on Monday afternoon.

In her first statement to the House as Prime Minister, Ms May will say: “We cannot compromise on our national security. We cannot outsource the grave responsibility we shoulder for keeping our people safe.”

"The nuclear threat has not gone away, if anything, it has increased".

She will also issue a stark warning to Labour leader Jeremy Corbyn, who has campaigned against nuclear weapons for decades, and has given his MPs a free vote on the issue,

“We cannot abandon our ultimate safeguard out of misplaced idealism,” she will say. “That would be a reckless gamble: a gamble that would enfeeble our allies and embolden our enemies. A gamble with the safety and security of families in Britain that we must never be prepared to take.”

Labour's shadow foreign and defence secretaries have allowed MPs to abstain in the vote, which is expected to take place at 10pm on Monday night, after a six-and-a-half hour debate. Renewing Trident is expected to cost more than £40bn.

Emily Thornberry and Clive Lewis say the vote is only occurring to capitalise on current divisions in the Labour Party. Renewal on Trident was already agreed in principle in 2007.

Deputy Labour leader Tom Watson has said the vote is “partisan political game-playing” but nevertheless said to abstain would be “abdication of responsibility”.

Emily Thornberry led a review into Labour's policy on Trident renewal, concluding that ‘underwater drones’ would render Trident as obsolete as the spitfire in the decades to come, remarks for which she was ridiculed by her party's MPs. But independent security experts have warned that advances in technology will make the location of permanently at sea submarines detectable far beyond the end of the planned lifespan of Trident.

The Scottish National Party, who are longstanding critics of Trident, will vote against renewal.

The party's leader at Westminster, Angus Robertson said the decision needed “proper scrutiny”.

“Trident is an immoral, obscene and redundant weapons system – and the decision on whether to renew it is one of the most important votes this Parliament will ever take,” Mr Robertson said.

“Having spent the best part of a month engaged in backstabbing, score-settling and navel-gazing, neither the Tories nor Labour are in any fit state to be giving proper scrutiny to decisions as important as this.”

The SNP has constantly criticised successive governments for operating Trident submarines from a base on the River Clyde in Scotland.

If the decision is taken to renew Trident, the replacement programme would be operational until the 2060s.