Trident: Deterring war or deterring votes?

Published Tuesday 2nd May 2017 by Daniel Kirkpatrick

Trident submarine
© Crown Copyright 2013

“I want us to achieve a nuclear-free world” - Jeremy Corbyn

“In the most extreme circumstances, we have made it very clear that you can’t rule out the use of nuclear weapons as a first strike” - Michael Fallon

Four submarines each capable of “266 times the destructive powers of the bomb that was dropped on Hiroshima” costing at least £31billion to build, and an estimated £100billion potentially to maintain over their 40 years of operational life [1]. This is what is being currently debated regarding Trident. So why do we need such a costly and potentially lethal weapon? Well the Conservatives, Liberal Democrats, and Labour have all committed to maintaining it, so let’s consider why.

Firstly, why have a nuclear weapon?

Trident is the UK’s nuclear deterrent; a weapon capable of mass destruction, designed to prevent other states who have similar weapons from using them against us (the UK). By equipping submarines with these weapons their location is unknown; meaning any strike against the UK would result in a retaliatory strike: second strike capability.

Secondly, do nuclear weapons work?

Well one study which looked at all international crises between 1945 and 2000 concluded that: “nuclear weapons do confer observable benefits to the possessors by making them less likely to be targets of violent aggression.” [2] In a similar study these authors also find that “crises involving nuclear actors are more likely to end without violence and, as the number of nuclear actors involved increases, the likelihood of war continues to fall.” [3] Test missile being launched from a submarineHaving nuclear weapons appears to therefore have a number of positive security benefits in terms of reducing potential aggression. But do these benefits really outweigh the massive economic costs which could be invested elsewhere, or indeed override the fundamental question of threatening nuclear Armageddon? This brings us to our third question:

Thirdly, what is the logic behind nuclear deterrence and does it work?

There are two main assumptions which nuclear deterrence relies upon: (1) that the threat is credible (that the state is both able and willing to launch a nuclear attack); and (2) that other states are deterrable (that the threat is sufficiently costly to outweigh any gains made from attacking) [4]. Having nuclear weapons therefore doesn’t automatically result in deterrence. The weapons must first be capable of inflicting sufficient damage on your opponent which is why there is such concern at present over the development of North Korean nuclear capability. Furthermore, you must convince your opponent that you would be willing to use them; if they don't believe you will then they won't be deterred. And lastly, even if you can demonstrate your threat and willingness to follow through with it, your opponent must then recognise that the threat posed will outweigh any potential gains.

Consider an analogy: a teacher says to his students that if they don’t submit an essay on time they will receive a mark of 0. Now for the threat to be credible the teacher needs to have the power to give marks and be willing to give a 0 if an essay is late. Furthermore, the students must determine that a late essay will definitely lead to a 0; that there’s no appeals process which would allow them to avoid such a sanction. If any one of these factors are missing the deterrent effect of the '0' will likely fail. So why then does this all matter? This brings us to my fourth and final point:

So finally and fourthly, what are the party policies at present towards Trident?

Graph displaying the policy positions of the main political parties in the UK towards Trident The credibility of the Trident has been a point of contention in recent news mainly because of Jeremy Corbyn’s guarded position on the issue. In an interview on the topic he explained: “I have made clear there would be no first use of it. I’ve made clear any use of nuclear weapons would be a disaster for the whole world.” [5] In his defence ruling out first strike capability doesn’t preclude a retaliatory strike. But Conservative critics are arguing that Corbyn is a “risk” [6] to national security because of his wider opposition to nuclear weapons and his call for a nuclear free world.

The Lib Dems have taken a slightly different position arguing that Trident needs to be scaled down. They have instead proposed to have ‘part-time’ deterrence with only 3 nuclear submarines [7].

The Green party are firmly opposed to Trident as an immoral weapon because it inherently relies on threatening mass destruction; whereas UKIP and the Conservatives are both fully in support of maintaining it. To help illustrate this I’ve put together a figure showing how these positions relate to one another (please see figure above).

So the question over which policy is best depends on a number of wider questions. Firstly do you believe nuclear weapons are ever justifiable? If not then only the Green Party would share your position. If on the other hand you accept they still represent a necessary, albeit morally reprehensible, deterrent, then you need to consider how important you feel they are; should investment decrease or be maintained? This then leaves the final question, the one of whether you believe the party leaders would be prepared to use nuclear weapons and, if so, when. If they aren’t then there’s no point having them because the credibility of the deterrent will become irrelevant.


[2] Beardsley and Asal (2009). “Nuclear Weapons as Shields”, Conflict Management and Peace Science, 26(3):235-255.

[3] Beardsley and Asal (2007). “Proliferation and International Crisis Behavior”, Journal of Peace Research, 44(2): 139-155.

[4] Achen and Snidal (1989). “Rational Deterrence Theory and Comparative Case Studies”, World Politics, 41(2)143-169.