What is Trident? The UK’s nuclear deterrent explained

The British parliament is due to vote on whether to renew Trident, the UK’s nuclear deterrent today. New Prime Minister Theresa May has said, “We cannot abandon our ultimate safeguard out of misplaced idealism. That would be a reckless gamble. The nuclear threat has not gone away. If anything, it has increased.“

But what is Trident and why is it controversial? Here’s a quick explainer about the UK’s nuclear deterrent, and what it means to the world and national security in 2016.

What is Trident?

Trident is the UK’s nuclear deterrent, and has been in place since the 1980s when it replaced Britain’s original Polaris missile system from the 1960s. It consists of four submarines each carrying missiles and nuclear warheads, to be deployed at a couple of days’ notice in the event of the UK being attacked by nuclear weapons.

It’s intended to be used as a last resort, and merely to act as a deterrent to other nations attacking the UK: a strategy known as “mutually assured destruction” whereby any nation launching a nuclear attack on Britain could expect the same devastation back in return.

That devastation would be severe: according to the BBC, each missile has a range of up to 7,500 miles and has a destructive power that is the “equivalent of eight Hiroshimas”.

What makes up the Trident nuclear system?

The Trident system, based in Faslane on the Clyde in Scotland, is composed of four submarines. Only one of these is deployed at any one time, with two being used for training and the other one undergoing maintenance. Each submarine can carry up to 16 missiles, which can each have a number of warheads that can be fired at up to 12 different targets.  

In practice, it’s unlikely that the submarines have ever run at this capacity, because Trident has only been operational at times of comparative military stability. Or as Tim Collins, a doctoral candidate at King’s College London studying Trident, told Gizmodo: “In practice we’ve never deployed that many. Trident came online as the Cold War was ending, and since then we’ve made further reductions… probably due to changes in strategic environment. The Cold War ends, do you really need this many?”

Britain is one of only eight countries confirmed to have a nuclear arsenal, with a handful of others suspected of having them. Among those nations, Britain is unique in that its nuclear deterrent is purely sea-based. While other nations have missile silos, armed bombers and ground-based launchers, Britain’s is purely at sea. The reasoning for this is that only a handful of people know where a British nuclear strike would come from at any given time, limiting the chances of a first strike taking out the country’s deterrent.

How would Britain launch a nuclear strike from Trident?

Should the prime minister (or an appointed deputy, should he or she be incapacitated) give the order for a nuclear strike to be sent, an encrypted message is sent through to the captain and their assistant. At this point they would retrieve codebooks from their safes and turn their keys at the same time for the nukes to launch. The idea is that one person can’t independently launch the system and bring about mass destruction.

If Britain were already destroyed – as the paranoia behind a round-the-clock nuclear deterrent suggests is entirely plausible – then those on the submarine turn to the famous “letter of last resort”. This is a note written by the prime minister upon taking office that instructs what to do in such an occasion. Nobody knows what these letters contain – naturally: to know would be to undermine the nature of the deterrent, should the prime minister decide there’s no point in retaliating.  

Anyway, if the prime minister gives the word – either alive or posthumously – preparation takes a few days, and the missile is then fired into space, where up to 12 warheads separate and head towards their intended targets. In theory if all four submarines were primed and ready to go, there could be 64 missiles packed with 768 warheads.

Why is the Trident nuclear deterrent in the news again?

In short, because Trident won’t last forever, and while its critics argue it’s a cold-war throwback, there’s still a strong majority – both in parliament and in the electorate at large – to renew the deterrent on national security grounds.

The current fleet has some life in it yet, with the submarines not expected to be replaced until the late 2020s, but the replacements could take 17 years to develop, so it is being discussed now.

Last time the issue came to parliament, MPs voted almost universally in favour of renewing the nuclear deterrent, with a government majority of 348. The issue is due to come again soon, and although a Conservative majority government ensures it’s unlikely to be voted down, it could be much closer thanks to the election of Jeremy Corbyn as Labour leader.

What are the main political parties’ position on Trident?

While there’s some debate within all parties about the ethics and sense of keeping a weapon that has failed if it ever needs to be used, you can broadly sum up the parties’ feelings over Trident as follows:

Conservatives: Strongly in favour of replacing Trident with a like-for-like replacement offering the same kind of cover.

Labour: Since briefly endorsing unilateralism in the early 1980s (a manifesto referred to as ‘“the longest suicide note in history’), the Labour Party has been in favour of renewing Trident and keeping Britain as a nuclear power. With the election of Jeremy Corbyn, things are somewhat more complicated, with the majority of MPs backing replacement, but the leadership and party activists seemingly against. An official line could be decided as soon as March, before parliament votes on it again. Expect rebellions if MPs are whipped to vote against renewal, though.

Scottish National Party: Strongly opposed to renewal, which is significant as the Trident fleet is stationed in Scotland. Has described Trident as “unusable and indefensible – and the plans to renew it are ludicrous on both defence and financial grounds”.

Liberal Democrats: Believes in scaling back the cost and scale of the deterrent, but maintaining some kind of nuclear-defence system.

UKIP: Like the Liberal Democrats, believes in a cheaper option. In 2015, mooted an “advanced stealth cruise-type missile” instead of the 24/7 at-sea deterrent.

Green Party: Strongly opposed. Party’s defence policies include “immediate and unconditional” nuclear disarmament.

Plaid Cymru: Has a “longstanding and unconditional” opposition to Trident.

What are the arguments in favour of Trident?

Trident’s supporters say that it’s essential for defending the UK against rogue states and terrorist groups, and that having a deterrent in place makes the country less likely to be attacked.

On top of that, stepping down from being a nuclear power would potentially reduce the country’s influence on the world stage.

Finally, the nuclear-defence industry is a major employer – not really a surprise given the scale of the deterrent. If Trident were scrapped, it’s estimated that around 15,000 jobs would be lost.

What are the arguments against Trident?

We’re not in the Cold War now. Modern threats to security are less likely to come from nations that could be deterred by the threat of a nuclear strike, but smaller terrorist groups of no fixed base. Critics argue that the threat of nuclear weapons is pretty empty because of this.

The costs are also hard to justify. At a time when everything from welfare to public health is undergoing belt-tightening, it’s increasingly hard to justify a weapon that is intended never to be used. Indeed, there are plenty of powerful countries in the world that get along just fine without nuclear weapons.

Finally, pretty much every major UK politician at least pays lip service to the idea of multilateral disarmament – the idea of scaling down the nukes on a global scale. It’s pretty hard to see how this goal can be achieved if no country is willing to take the first step and unilaterally disarm.

How much would Trident cost to renew?

The government says a Trident replacement would cost £15-20bn, although others argue it could be anywhere up to £100 billion. In any case, it’s hugely expensive, with the MoD confirming that as things stand, the deterrent takes up 6% of the country’s total defence budget.

How many times has Britain launched nukes?

The UK has undertaken around 45 nuclear tests – the same number as China, but far less than France, the USA and Russia. You can see a full video of all the detonations by year in this mesmerising video.

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Images: Defence Images, The Weekly Bull, Mark Ramsay, Lucy Haydon, Defence Images, Defence Images, Defence Images, used under Creative Commons