'You do believe in the nuclear deterrent?'

Whom or what exactly do our Trident nuclear submarines deter?

This was the question I posed earlier on Twitter, swiftly generating a few responses.

Answers included ‘MOD spending cuts’, ‘fish mostly’, and one from my most hawkish friend which read ‘At the moment, nothing. In the future, possibly the Iranians, Chinese, North Koreans, French, Germans’ - I think he pines for the days when you only needed to have a shufti across the Channel if you fancied a bit of swash and buckle.

The logic of maintaining a nuclear deterrent during the Cold War, while much debated, was at least clear. Indeed, it can be argued that the threat of Mutually Assured Destruction, acknowledged by all sides, prevented leaders from going that fateful extra step in one of the many moments of high tension. But, these days it is hard to identify a single country vaguely deterred by our nuclear arsenal whatsoever.

Defence secretary Philip Hammond was pretty clear on the Today programme that now is not the time to downgrade our nuclear options. He said: 

‘We have had for 45 years now a continuous-at-sea deterrent posture which has served this country very well and we do not believe that with nuclear threats, if anything, proliferating, with more countries seeking to get nuclear weapons, this is the time to downgrade, certainly not to go to a part-time deterrent.’

But this argument simply isn’t coherent. In his very comments, Hammond exposes the intellectual dishonesty of the deterrent claim. Despite our ‘continuous-at-sea’ posture, no country has been deterred from seeking a nuclear weapon. Proliferation has, as the minister acknowledges, continued. If anything our retention of nuclear weapons has simply spurred others on to join the club.

After all, does Iran, pressing on with its nuclear programme, look over its shoulder nervously, worried if a British submarine might rise in the Strait of Hormuz? Seems unlikely. North Korea appeared perfectly happy to indulge in a bit of silly sabre rattling, making all sorts of wild claims about its military capabilities, regardless of Britain’s nuclear weapons. But the government remains committed to spending billions – some claim up to £100billion over 30 years – on a new generation of weapons just in case.

And then there is the question of whether a Prime Minister, or defence minister would actually press the button if such terrible circumstances arose.

A few years ago Denis Healey, who served as defence secretary under Harold Wilson, was asked this very question. If Britain had been attacked and Wilson had been killed, Healey would have been the minister to go to the Royal Air Force’s Bomber Command bunker and trusted with the decision as to whether to retaliate. This is what Lord Healey said:

‘I did feel rather worried about it because I knew it would be a very difficult decision to take. I realised I would find it very, very difficult indeed to agree to use a nuclear weapon – and I think most people would.’

Further pressed, Healey was asked what if the head of Bomber Command told him Russian nuclear weapons were already raining down on targets across the country. He replied: ‘I think I would still have said that that, I’m afraid, is no reason doing something like that. Because most of the people you kill would be innocent civilians.’

Lord Healey is hardly a shrinking violet and any minister today would face an even trickier decision. For Healey was talking about days when an enemy could be clearly identified; that is no longer the case. Yes, rogue states can be counted simply enough but one of one of the biggest nuclear threats facing the UK comes from rogue individuals and terrorist organisations who have no country allegiance. It would, for example, be inconceivable to launch a nuclear retaliation on Pakistan if Al Qaeda terrorists from there successfully detonated a device in London.

Of course what this is really about is prestige. Both major political parties know that in order to maintain any international authority retaining nuclear armed submarines is necessary. Whether Britain needs to play such a major role on the international stage is another debate entirely. But it would be good if those pushing to spend such vast sums of money on military toys would at least be honest about their motives.