What is a letter of last resort, what is Trident and what happens in the event of nuclear war?
TRIDENT - Britain's nuclear deterrent is currently gliding deep beneath the waves, ready to launch a devastating strike at a moment's notice.
But what is exactly is it, what is a letter of last resort and what happens in the event of nuclear war?
What is Trident?
Trident is the name of Britain's nuclear deterrent, which consists of four deep sea craft mounted with eight ballistic missiles each.
At any given time, one of the Vanguard-class submarines is on patrol, with the others either recovering from their last deployment or being prepared for their next stint at sea.
The continuous deterrent would allow British generals to launch a nuclear attack at a moments notice, using the submarines to deliver a deadly nuclear payload to targets across the globe.
What is a letter of last resort?
They are four identically-worded handwritten letters from the Prime Minister to the commanding officers of the four Trident subs to be opened if a nuclear strike wipes out the British government - including the PM and other high-ranking Cabinet members.
The letters are kept in a safe and are destroyed without being opened after the Prime Minister leaves office.
What do letters of last resort say?
Only the Prime Minister who wrote them knows exactly what they say - but the 2008 BBC Radio 4 documentary The Human Button reports there were four options given to the PM. These are:
- Retaliate with nuclear weapons
- Do not retaliate
- Use their own judgement
- Put the submarine under an allied country's command (potentially the US or Australia)
What is the case for and against Trident and why is it so controversial?
There are several arguments for and against Trident as the current generation of submarine’s shelf-life will come to an end in the late 2020s.
Work on a replacement system should start as soon as possible as the submarines alone could take up to 17 years to develop.
Some pro-Trident activists say the submarines are pivotal to UK security as we face an “uncertain threat environment.”
It isn’t possible to pinpoint or predict the emergence of nuclear threats in the future.
Therefore, some argue that it should be ensured that the UK has future options available for defence and deterrence in the future.
The nuclear defence industry is aso a major employer - with estimates that 15,000 jobs may be lost if plans for a new batch of submarine isn’t put in place.
Arguments against the set of submarines largely fall on two sides - moral objections or financial objections.
For instance, Labour leader Jeremy Corbyn has made it clear that his pacifism means he could never be the one to press the button.
He said if he became PM, the country’s crucial defence system would be on the table in international negotiations as he pledged to give “realism to the nuclear non-proliferation treaty”.
Jeremy Corbyn said he would appoint a Minister for Peace if he ever got into power with a brief to "reduce violence, war and conflict".
And he also refused to rule out scrapping Trident unilaterally as a price for securing the SNP’s support in the event of a hung Parliament after the election.
Others argue Trident’s £40bn price tag is too high for a project that is in place for unpredictable threats and an “uncertain future environment."
What are the alternatives?
One alternative that has been suggested is to use cruise missiles instead of the current, much longer range ballistic missiles.
A government body concluded this would actually be more expensive in the long run, however since the UK may have to bear research and development costs.
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Others have suggested a land-based delivery system rather than the much more expensive submarine system.
A third alternative option would be to shoot the missiles from a long-range aircraft.
However, all alternatives need more development and planning before they could be real, practical solutions.
