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Commemorating 50 Years of Royal Navy CASD By Howard Wheeldon, FRAeS, Wheeldon Strategic Advisory Ltd.




Later this morning, a service of commemoration marking 50 years of continuous-at-sea nuclear deterrent capability (CASD) will be held at Westminster Abbey:

A defence strategy that has for the past 50 years been pursued by successive Labour, Conservative and Coalition Governments, one that at its heart has maintaining at all times a British minimum strategic nuclear retaliatory capacity, the Royal Navy has since 1969 provided the nation with continuous at sea nuclear deterrent (CASD) capability – 24 hours a day, 365 days a year – and importantly, will continue to do so for decades ahead.

The four Royal Navy nuclear powered Vanguard-class submarines currently in service are designed not only to patrol the world’s oceans silent and undetected but also to be able to strike at any time demanded. Each vessel, HMS Vanguard, HMS Victorious, HMS Vigilant and HMS Vengeance, carries Trident nuclear missile system capability. Not only do these vessels provide vital defence capability for the UK as a whole but they also send a powerful message to any would-be adversary or others that would do us harm. CASD in my view has represented and will continue to represent not only the cornerstone of UK defence policy but also provide a major contribution to the Alliance’s deterrent forces.    

The Royal Navy has been responsible for providing the UK’s strategic nuclear deterrent capability since April 1969. It does so with a minimum of one of the four ballistic missile submarines on patrol at any one time in an operation known as ‘Relentless’. Most usually referred to as continuous-at-sea deterrent or (CASD), this was originally provided by four Resolution-class nuclear powered submarines carrying Polaris ballistic missiles. The Royal Navy had formally assumed responsibility for the UK’s strategic nuclear deterrent in June 1969, taking over from the Royal Air Force V-force. UK nuclear deterrent capability has been solely submarine-based since the withdrawal of Royal Air Force WE-177 free-fall bombs in the late 1990s.

CASD is, as mentioned above, provided today by the four Vanguard-class submarines carrying the Trident missile system. In July 2016 the House of Commons voted to approve the decision to maintain the UK’s nuclear deterrent beyond the early 2030s. To that end, the four Vanguard-class submarines will be replaced by the new Dreadnought-class vessels to be built by BAE Systems at the company’s state-of-the-art Barrow-in-Furness submarine yard. The first Dreadnought-class vessel is expected to enter service in the early 2030s and have a service life of at least 30 years. So far, three of the planned four Dreadnought submarines have been named – HMS Dreadnought, HMS Valiant and HMS Warspite.

The cost of the design and manufacture of a class of four submarines has been estimated at £31 billion, including defence inflation over the life of the programme. A £10 billion contingency has also been set aside. Once the new nuclear deterrent comes into service the annual in-service costs are expected to continue at approximately 6% of the defence budget.

The UK is separately participating in the US’ current service-life extension programme for the Trident II D5 missile, which will extend the life of the Trident missile potentially to the early 2060s. Decisions on a replacement warhead have also been deferred until later in this Parliament.

The military argument that supports maintaining a minimum strategic nuclear retaliatory capability are, to me, unquestionable. They comprise the underlying argument that future military threats and conflicts will be no more predictable in the future than they have been in the past. The overriding justification of nuclear deterrent capability is little different than reasoning why we maintain a strong military capability in land, air and sea – all serve to provide insurance against attack. But above all, maintaining nuclear deterrent capability deters other states from credibly threatening us with similar weapons of mass destruction. The UK has of course long been an advanced nation in respect of the defence capability it has but we must also always recognise that others are catching up.

In making my case for the importance of retaining continuing nuclear at sea deterrent capability I can do no better than repeat the wise words of Julian Lewis MP, also chair of the House of Commons Defence Select Committee and who I recall three years ago in a debate in the House of Commons on Trident Nuclear Deterrent Renewal said:

“It is not the weapons themselves that we have to fear but the nature of the regimes that possess them. Whereas democracies are generally reluctant to use nuclear weapons against non-nuclear dictatorships – although they did against Japan in 1945 – the reverse is not the case. Let us imagine a non-nuclear Britain in 1982 facing an Argentina in possession of a few tactical nuclear bombs and the means of delivering them. Retaking the islands by conventional means would have been out of the question! ​

The UK he said “has traditionally played a more important and decisive role in preserving freedom than other medium-sized states have been able or willing to do. Democratic countries without nuclear weapons have little choice but to declare themselves neutral and hope for the best, or to rely on the nuclear umbrella of powerful allies. The UK is a nuclear power already, and it is also much harder to defeat by conventional means because of our physical separation from the continent”.

“Our prominence” he said “as the principal ally of the United States, our strategic geographical position and the fact that we are obviously the junior partner might tempt an aggressor to risk attacking us separately. Given the difficulty of overrunning the United Kingdom with conventional forces, in contrast to our more vulnerable allies, an aggressor could be tempted to use one or more mass destruction weapons against us on the assumption that the United States would not reply on our behalf. Even if that assumption were false, the attacker would find out his terrible mistake when and only when it was too late for all concerned. An independently controlled British nuclear deterrent massively reduces the prospect of such a fatal miscalculation”.

The final military argument Mr. Lewis put forward was that “no quantity of conventional forces can compensate for the military disadvantage that faces a non-nuclear country in a war against a nuclear-armed enemy. The atomic bombing of Japan is especially instructive not only because the Emperor was forced to surrender, but because of the reverse scenario: if Japan had developed atomic bombs and the Allies had not, an invasion of Japan to end the war would have been out of the question. The reason why nuclear weapons deter more reliably than conventional ones, despite the huge destructiveness of conventional warfare, is that nuclear destruction is not only unbearable, but unavoidable once the missiles have been launched. The certainty and scale of the potential retaliation mean that no nuclear aggressor can gamble on success and on escaping unacceptable punishment”.

Rapping up his part in the debate he said that “Opponents of our Trident nuclear deterrent capability say that it can never be used. The two thirds of the British people who have endorsed our keeping nuclear weapons as long as other countries have them, and continue to endorse that in poll after poll – as well as in two general elections in the 1980s – are better informed. They understand that Trident is in use every day of the week. Its use lies in its ability to deter other states from credibly threatening us with weapons of mass destruction. Of course, the British nuclear deterrent is not a panacea and is not designed to forestall every kind of threat, such as those from stateless terrorist groups, but the threat that it is designed to counter is so overwhelming that no other form of military capability could manage to avert it”.

“If” he said “the consequence of possessing a lethal weapon is that nobody launches it, while the consequence of not possessing it is that someone who does launches it against us, which is the more moral thing to do – to possess the weapon and avoid anyone being attacked, or to renounce it and lay yourself and your country open to obliteration? If possessing a nuclear system and threatening to launch it in retaliation will avert a conflict in which millions would otherwise die, can it seriously be claimed that the more ethical policy is to renounce the weapon and let the millions meet their fate? Even if ​one argues that the threat to retaliate is itself immoral, is it as immoral as the failure to forestall so many preventable deaths”?

“The final Moral choices are, more often than not, choices to determine the lesser of two evils. The possession of the nuclear deterrent may be unpleasant, but it is an unpleasant necessity, the purpose of which lies not in its ever being fired but in its nature as the ultimate insurance policy against unpredictable, future, existential threats. It is the ultimate stalemate weapon, and in the nuclear age stalemate is the most reliable source of security available to us all”.

CHW (London – 3rd May 2019)

Howard Wheeldon FRAeS 

Wheeldon Strategic Advisory Ltd,

M: +44 7710 779785

Skype: chwheeldon



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