The Prime Minister delivered the news during a speech at the Conservative conference in Manchester on Wednesday.

Peter Byrne / PA Wire/PA Images

Prime Minister David Cameron has reaffirmed his support for Trident by again pledging to renew Britain's nuclear deterrent.

Mr Cameron delivered the pledge during a speech at the Conservative conference in Manchester on Wednesday.

He said the UK Government would order four new replacement submarines, calling them Britain's "ultimate insurance policy".

The Prime Minister told the conference: "We will spend 2% of our GDP on deference this year, next year, and throughout this decade.

"Because our nuclear deterrent is our ultimate insurance policy, this government will order four new trident submarines."

The SNP wants to scrap the controversial nuclear weapons scheme, which is based at HM Naval Base Clyde at Faslane.

Labour leader Jeremy Corbyn has said he does not believe Britain should spend £100bn renewing Trident and would not use nuclear weapons if he was elected Prime Minister.

Meanwhile, Mr Cameron said Britain must “play its part” in the fight against Islamic State in Syria.

Ministers are seeking Labour backers for a Commons vote on extending the role of UK armed forces beyond Iraq despite, Labour's resistance to the move.

Defence secretary Michael Fallon said the UK Government would only seek approval "when we are sure we are going to win it" after Mr Cameron was defeated in 2013 over a similar escalation.

He said the start of Russian air strikes on IS, which western intelligence suggests have hit moderate opponents of Syrian president Bashar Assad, had "made a pretty difficult situation much more dangerous".

But Mr Cameron told the Conservative Party conference: "The real answer to the refugee crisis lies in helping countries like Syria become places where people actually want to live.

"That means having a government that's not terrorising its people - and that's why Assad must go.

"In its place, we need a government that can be our ally in the defeat of Isil because we will never be safe here in Britain until we eradicate that death cult.

"Some think we can contract that out to America. We shouldn't. We must play our part too."

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