Lifting cap on nuclear weapons is 'ultimate insurance policy', says Foreign Secretary Dominic Raab

The test firing of a Trident missile Credit: PA

Lifting the cap on the UK's stockpile of nuclear weapons is the "ultimate insurance policy" against threats from hostile states, the foreign secretary has said.

Dominic Raab said it was important to maintain a “minimum credible level of deterrent” amid reports Boris Johnson is set to raise the cap on Britain’s stockpile of Trident nuclear warheads, ending three decades of gradual disarmament.

The government’s Integrated Review of security, defence, development and foreign policy will increase the limit from 180 to 260 warheads, according a leaked copy obtained by the Guardian.

The paper said that it paves the way for a £10 billion rearmament in response to perceived threats from Russia and China.

Asked why the Government would want to increase the amount, the Mr Raab told BBC Radio 4’s Today programme: “Because over time as the circumstances change and the threats change, we need to maintain a minimum credible level of deterrent.

“Why? Because it is the ultimate guarantee, the ultimate insurance policy against the worst threat from hostile states.”

HMS Vigilant carries the Trident missile, the UK’s nuclear deterrent Credit: James Glossop/The Times/PA

Asked by ITV News why other counties should stick to nuclear non-proliferation commitments if the UK is going to increase its number of warheads, Mr Raab said the government wants "to see a nuclear-free world, but we're also not naive about the threats we face".

He added that the UK has "only ever committed to maintaining a minimum credible deterrent" and the government takes "into account the changing circumstances in the world and the threats we face as to what that minimum is and how credible it needs to be, but of course we fully comply with our international obligations".

The Treaty on the Non-Proliferation of Nuclear Weapons, of which the UK is a signatory, aims to prevent the spread of nuclear weapons and technology worldwide, with the ultimate aim of complete nuclear disarmament.

Elsewhere the review is said to warn there is a “realistic possibility” that a terrorist group will launch a successful chemical, biological, radiological or nuclear (CBRN) attack by 2030.

The prime minister will set out the findings of the year-long survey – billed as the most radical reassessment of Britain’s place in the world since the end of the Cold War – in the Commons on Tuesday.

It is expected to include the creation of a new state-of-the-art counter-terrorism operations centre to streamline the response of police and the intelligence agencies in the event of an attack.

The will also be a new “situation centre” in the Cabinet Office similar to the White House situation room where Barack Obama was able to watch the US special forces operation to kill Osama bin Laden in real time.

Boris Johnson Credit: Peter Morrison/PA

The 100-page document – entitled Global Britain in a Competitive Age – argues the increase in nuclear warheads cap is “in recognition of the evolving security environment” and the “developing range of technological and doctrinal threats,” the Guardian said.

“A minimum, credible, independent nuclear deterrent, assigned to the defence of Nato, remains essential in order to guarantee our security and that of our allies,” the review says.

The review states that Russia under Vladimir Putin represents an “active threat” however the language on China is more measured, saying Beijing poses a “systemic challenge”.

Speaking to ITV News, Mr Raab said he believes Russia "remains a threat" in terms of "cyber, the threat of their aggression as we have seen in Ukraine, the threat of propaganda and misinformation is huge.

"We need to be clear sighted about that - work with our international allies and be totally robust."

Reacting to the review, Sir Alex Younger, former head of MI6, said Russia was “implacably hostile” to the UK and its allied countries, while China represented a “generational threat”.

China and Russia have been forming closer ties in recent years. Credit: AP

He told BBC R4’s Today programme: “There’s no doubt that China represents the generational threat and the reason for that is that the idea that China will become more like us as it gets richer, or as its economy matured, is clearly for the birds.

“That’s not going to happen. On the contrary I expect China’s Communist Party to double down on its ideology in the future.

“There’s going to be an ideological divergence between us in the future, that’s going to generate rivalry and reduce trust.”

According to The Times, which has also obtained a leaked copy of the review, it says the UK will “not hesitate” to defend its values and will increase the protection of critical infrastructure, such as the national grid, transport and water supplies.

However, in a section on China which is likely to alarm Tory hawks, the review is said to argue that the UK will need to pursue a positive economic relationship including “deeper trade links and more Chinese investment”.

Elsewhere, it marks a strategic “tilt” towards the Indo-Pacific region, reflecting the view of ministers that it is increasingly becoming the “geopolitical centre of the world”.

The shift will be underlined by the deployment of the HMS Queen Elizabeth carrier strike group to the region on its maiden operational mission later this year.

It is also said to include a personal commitment from the prime minister to to restore foreign aid spending to 0.7% of national income “when the fiscal situation allows” following furious criticism of cuts to support for Yemen and other countries.

In a Commons statement, Mr Johnson is expected to argue that while Nato remains the bedrock of UK security in the Euro-Atlantic region, the country can no longer rely on an “increasingly outdated international” to protect its interests.

At a time when some countries are seeking to undermine the open and liberal international order which emerged following the Cold War, he is expected to say the UK needs to use “all the tools at our disposal” to ensure a world where democracies can still flourish.

He is expected to tell MPs: “I am profoundly optimistic about the UK’s place in the world and our ability to seize the opportunities ahead.

“The ingenuity of our citizens and the strength of our Union will combine with our international partnerships, modernised armed forces and a new green agenda, enabling us to look forward with confidence as we shape the world of the future.”

The publication comes after the Prime Minister announced in November a £16.5 billion increase in defence spending over the next four years focusing on the future battlefields of space and cyber.

However, military chiefs have made clear the investment in new technologies will mean cuts to some “industrial age” capabilities to be set out in further paper by the Ministry of Defence next week .

The Army is expected to be the biggest loser with troop numbers expected to be slashed by more than 10,000, while its fleet of Challenger 2 main battle tanks is expected to be reduced by a third and the Warrior infantry fighting vehicle retired altogether.

For more politics news, listen to the ITV News Calling Peston podcast: