Nuclear weapons and the ‘Letter of last resort’: what my students think

By Jez Littlewood

NPSIA’s disarmament, arms control and non-proliferation course began last week (INAF 5201). Once the administrative side of the first class was completed I began the class with the 2015 Bulletin of the Atomic Scientists What would happen if an 800-kiloton nuclear warhead detonated above midtown Manhattan? However, to inject some additional reality into the subject each was tasked with deciding on how the UK would respond to a nuclear attack.

The scenario was simple: each was to assume they had been elected (or appointed) Prime Minister of the United Kingdom and each had to decide the nuclear response in the event of a surprise attack. Pre-reading included Richard Norton-Taylor’s story in The Guardian from July 2016 – Theresa May’s first job: decide on UK’s nuclear response. Thus, sixty minutes after arriving in class task one for my 21 students was the drafting of what is generally known as “the letter of last resort”.

Norton-Taylor and others report Tony Blair went white and Peter Hennessy indicates John Major subsequently cancelled a planned weekend event to return home to his constituency. Nuclear war planning has many facets, but given the US election and differing views on the suitability (or not) and rationality (or lack of) of the two leading Presidential candidates the question of who has a finger on the nuclear button is not an abstract issue. There is no “button” per se, but I wanted my students to understand the realities of authorizing such a strike and underline that there is a procedure involved that has been thought out and practiced. At least in the UK, and probably in the US, war planners have considered a wide variety of challenges over the years including, as Hennessy notes in his The Prime Minister: ‘what if the Prime Minister goes bananas (as the Chief of the Air Staff said of Eden in July 1956?)’

As Norton-Taylor outlines the general understanding of the process of writing the Letter of last resort is as follows: ‘One of the first tasks to confront a new prime minister, after an audience with the Queen, is to write “the letter of last resort”. …Theresa May will be asked to write to (unnamed) commanders of a Trident missile submarine on patrol in the Atlantic. The letter will tell them whether or not, after a devastating attack on Britain, she (by this point either dead, or uncontactable) would be willing to retaliate by firing a nuclear missile. May will be asked to write the letter as soon as she takes office, after being “indoctrinated” by the chief of the defence staff, Sir Nicholas Houghton, who will explain precisely what damage a Trident missile could cause.’

Peter Hennessy has written on UK nuclear planning in The Secret State and The Prime Minister, but I used the more recent The Silent Deep as principal background for developing a 15 minute brief for the students on what the UK nuclear deterrent force can do, as well as what it is for.

Hennessy and Jinks in their history of the Royal Navy Submarine Service (The Silent Deep) allow official documents to speak for themselves. The ‘Duff-Mason’ report (in the Towards Trident section of chapter eight) entitled Factors Relating to Further Consideration of the Future of the United Kingdom Nuclear Deterrent (1978) provided the evidence related to UK criteria for deterrence, judgements on “unacceptable damage” to the adversary – at the time the Soviet Union – and the ‘three broad options for creating unacceptable damage.’ Coupled with the UK’s report to the last review conference of the Nonproliferation Treaty (NPT) which provided some detail on current UK nuclear posture, and other sources including the Campaign for Nuclear Disarmament 2013 report If Britain fired Trident the brief outlined the existing UK deterrent force of four Vanguard class submarines, Trident D5 missiles and the nuclear warheads, the requirement for continuous at sea deterrence, i.e. one submarine on patrol at all times, and the procedure for the Prime Minister to authorize a nuclear response and the military chain of command to issue such an order. As Hennessy and Jinks note ‘a UK Prime Minister can change the world – and our country – for ever inside an hour.’ (675)

In basic terms I described UK documents of that time (1978) as follows.

“three options to create ‘unacceptable damage’

• “destruction of main Government centres (both above and below ground) within the Moscow outer ring road and outside it, a selected number of alternative bunker locations…associated with the centralised system of command and control…;
• Breakdown level damage to Moscow as a city and Leningrad and two other large cities;
• Damage to a number of cities, but excluding Moscow. Two variants are suggested –
  • Breakdown level damage to Leningrad and about 9 other major cities;
  • Grave damage, not necessarily to breakdown level, to 30 major targets, including Leningrad and other large cities and possibly selected military targets.”

Basically, option one involves ground bursts on Moscow, widespread destruction of Moscow, and a significant fallout hazard; option two involves damage beyond repair 50% of buildings in 4 major cities, that are major centres of military research, development and production with an estimate of five million dead and four million further casualties; and, option three provides an ability to target all cities with population greater then 500,000 West of Urals to achieve damage similar to option two. It would require attacks on Leningrad and about 9 other major cities.

Combining this with RUSI’s 2011 report on Small Nuclear Forces, the Scottish CND publication If Britain fired Trident, International Campaign to Abolish Nuclear Weapons summary of effects of a 100 Kiloton warhead and The primary objective was to underline to my students what nuclear weapons can do and that the UK nuclear deterrent is understood to be a counter-value force targeting cities and populations.

Unlike the UK Chief of Defence Staff (CDS) I do not know what, precisely, Trident can do, but by combining non-governmental and advocacy material with scholarship and history and official documents the objective of the brief was to inject reality into future discussions in the class.

Twenty-one students were present and all submitted hand-written letters of last resort to me half-way through the class. Norton-Taylor reports that the ‘options are said to include the orders “Put yourself under the command of the US, if it is still there”; “Go to Australia”; “Retaliate”; or “Use your own judgment”.’ So what did my students write in their own letter of last resort?

Overwhelmingly the instruction was for the submarine Commander to use their own judgement, ascertain as many facts as possible, including the identity of the attacker, and place themselves under the command of the US or another allied state. Of the latter Australia was most frequently mentioned, but both Canada and New Zealand were identified by some students, and France was chosen by two authors. Very few opted for ‘retaliate’ without explicit consultations with allied states and all of these made clear that the Commander should retaliate only if the aggressor could be identified. Moreover, within the letters was a recognition that deterrence had failed and, therefore, targeting military forces rather than cities and populations should be considered. Some specifically wrote that retaliation as vengeance was not permitted: indeed, most specifically wrote that any retaliation must serve a purpose in the interests of saving lives of remaining UK nationals or those of allied nations and/or halting conflict.

As an exercise for my students it was, of course, imperfect, but the intention was to require them to think about the actual realities of nuclear weapons and nuclear deterrence before the course delves into issues in greater detail.

Whether or not their views will change or be refined remains to be seen. In the penultimate class they explore the case for nuclear disarmament, the international campaign to abolish nuclear weapons and the objective of ‘Global Zero’. I will then return their handwritten letters to each of them.