By Julian Lewis & John Woodcock

Prospect Magazine – May 2022 [published online on 7 April 2022]

Three days after Putin’s invasion of Ukraine, the Russian dictator declared that his nuclear forces would be placed on "a special regime of combat duty", implying an increased state of readiness to launch. Given the need for any nuclear deterrent to be ready to retaliate at short notice, this announcement was virtually devoid of meaning. Yet it serves to remind us of repeated campaigns – in the 1960s, 1980s and quite recently – to abandon the British deterrent, and the relief we should feel at successfully resisting them.

Our shared cause triumphed on 18th July 2016, when the House of Commons decided, by an overwhelming 355-vote majority, to replace fully the Royal Navy’s four ageing Trident submarines. It had been a  long  journey from the initial vote held on 14th March 2007 to begin the process. Then the majority was 248 – itself an indication of very strong cross-party support for renewal. This continued to grow in the following parliament, despite David Cameron’s extraordinary concession of a four-year postponement of the final decision as part of his 2010 coalition deal with the anti-Trident Liberal Democrats.

That delay, from 2012 to 2016, went ahead regardless of an anticipated extra cost to the country of up to £1.4bn. It also put the entire deterrent at risk, if another hung parliament had been elected in 2015, and if the Liberal Democrats had sought Trident’s cancellation as their price for continuing the coalition. Defence-minded Conservative and Labour MPs were appalled at this prospect.

What is it about strategic nuclear weapons that makes them so central to our security? Their potential destructiveness is only part of the answer. Terrible destruction was wreaked on German and Japanese cities by conventional bombing in the Second World War, but that alone did not induce surrender. By contrast, the atomic bombing of two Japanese cities, three days apart, forced the emperor to capitulate almost at once.

In conventional mass bombing, success could not be guaranteed: the attackers might be destroyed and the target might survive. With atomic bombing, there was no possibility of that outcome: a single bomb would inevitably cause utter devastation. In a nuclear exchange, the consequences would not only be unacceptable, but also unavoidable. Hence the unfortunate acronym of "MAD" – in a war between nuclear powers, the "destruction" would not just be "mutual", but "assured".

Did this prevent all-out war between east and west until the collapse of Soviet communism? The only way to prove that absolutely would have been to disarm unilaterally and wait for the worst to happen – a choice, thankfully, which we never made. The Cold War remained frozen in Europe, where the nuclear stalemate applied, while numerous conventional conflicts were fought, often by communist and western proxies, in parts of the world where nuclear confrontation was absent.

Such an outcome had been anticipated: in October 1945, in a top-secret memorandum for an inquiry into the future nature of warfare, Professor George Thomson suggested that in the nuclear age,

"a nation may be prepared to use force, but not to the extent of accepting the almost certain destruction of most of its towns."

He even predicted that

"if major powers had atomic bombs and minor ones not, there would be a temptation for a major power to push a small one forward and help it in a war against the protégé of its rival … without exposing itself to atomic bombs."

That such proxy contests occurred so often outside Europe during the Cold War strongly suggests that fear of mutual annihilation helped the avoidance of open warfare inside Europe between the superpowers.

The primary purpose of a nuclear deterrent in the hands of a democracy is to minimise the risk of being attacked by mass-destruction weapons in the hands of an enemy. It is not a panacea, and it cannot be relied upon to forestall every type of threat. For most of the Cold War, the Soviet-controlled Warsaw Pact was deemed capable of overrunning continental Europe with conventional forces alone. If the worst happened, the British strategic deterrent would be the key to survival pending the arrival of US reinforcements.

During the 1980s, frequent polling consistently showed that two-thirds of the British people wanted the UK to continue to possess nuclear weapons as long as the USSR had them, while only a quarter desired their unilateral renunciation. Very few were undecided. If a similar poll were held in Ukraine today – had it not given up the large nuclear stockpile it had inherited from the Soviet Union – it is beyond doubt that even larger numbers favouring a nuclear deterrent would be recorded.

With the publication of the Integrated Review of  Security, Defence, Development and Foreign Policy in March 2021 came the announcement that – instead of being reduced from a maximum of 225 nuclear warheads to no more than 180, as previously intended – our total nuclear stockpile would rise to a maximum of 260. That figure, if reached, would still leave us with fewer warheads than either France or China, let alone the colossal “overkill” capability of the United States and Russia. But since only a fraction of our warheads would have to reach the target in order to inflict unacceptable and unavoidable destruction, other countries' totals are irrelevant.

Our policy of strategic minimum nuclear deterrence comprises the ultimate insurance policy against nuclear blackmail or attack. We should be proud to pay the premiums and grateful to previous governments for giving us the opportunity to do so.

Julian Lewis is Conservative MP for New Forest East and formerly chaired the Defence Select Committee

John Woodcock was Labour MP for Barrow and Furness, where the Trident submarines are built, and now sits as a crossbench peer