Commentary 21 - April 2026

Nuclear Deterrence

“A world without nuclear weapons may be a dream but you cannot base a sure defence on dreams. Without far greater trust and confidence between East and West than exists at present, a world without nuclear weapons would be less stable and more dangerous for all of us.”

These words were spoken by Margaret Thatcher on her visit to Moscow on March 30, 1987. We now know that the days of the Soviet Union were numbered. In the post-Cold War period, many hoped for a new era in international relations, and so it seemed for a period. But the increasingly belligerent tone taken by Vladimir Putin has ended that hope. Following the full scale invasion of Ukraine in February 2022, Thatcher’s words echo down to us across the years.

Following Putin’s invasion of Ukraine, Moscow has rattled the nuclear sabre several times via the channel of Putin’s trusted commentators. Suddenly we are back in the bad days of the 1980s. The UK government’s Strategic Defence and Security Review of 2025 reiterated the need for the UK to maintain the credibility of the continuous at sea deterrence which has been operating since 1969. It also undertook to sustain the Defence Nuclear Enterprise, which provides the industrial and scientific capacity needed to sustain the deterrent.

In June 2025 the UK government announced the purchase of an additional 12 F 35 aircraft, the A version, which will be part of NATO’s DCA force. These Dual Capable Aircraft will have the capability to operate with US supplied B 61 nuclear munitions, which are forward deployed in Europe. The DCA force is a measure designed to provide a tactical nuclear capability, in addition to the ‘last resort’ capability provided by Trident.

Cost

According to a House of Commons Library research briefing of August 2025; “The SDR says that £15 billion will be committed to the replacement warhead programme in this Parliament.”

It goes on:

“The decision to amalgamate nuclear spending under one budget heading: the Defence Nuclear Enterprise (DNE), reflects the increasing interdependence between the nuclear deterrent and the Royal Navy’s other conventionally armed nuclear-powered submarine programmes, including the new AUKUS SSN being developed in conjunction with the US and Australia. This is particularly relevant to the costs associated with basing, infrastructure and nuclear propulsion…… Spending on nuclear programmes across of the whole Defence Equipment Plan to 2033 is currently forecast at £128 billion. That represents a £10 billion increase on the original forecasts in the 2023-2033 equipment plan.”

Thus, the cost of the nuclear deterrent on a stand alone basis is obscured. It has previously been stated that the operating cost of the Deterrent amounted to around 6% of the total defence budget. In 2023 the UK government agreed to pay £12 million annually towards the cost of the Strategic Weapons Facility at King’s Bay Georgia, where the Trident missiles are stored and maintained. Development of the UK’s nuclear warhead remains a sovereign capability.

Over recent years there have been several discussions between the MOD and the Treasury about funding the cost of the Deterrent programme. The question being how to prevent the Deterrent costs eating into the MOD’s overall Equipment Plan (EP) for conventional capability. The resultant fudge means that the future EP will always be subject to the outflows required for elements of the DNE.

Discussion

Following the return to office of Donald Trump as US president, there has been much turbulence in the international arena. In respect of the on-going war in Ukraine, European leaders remain focussed on the threat from Russia. Alongside increases in expenditure and conventional capability among members of NATO – Europe (which includes the UK), there has been movement on the nuclear front too. In July 2025 the UK and France as nuclear weapon states announced greater co-operation on nuclear matters. In March 2026 president Macron announced a new French nuclear doctrine which would see French nuclear assets placed at the disposal of allies in a time of crisis, although these assets would remain under French command.

If deterrence is to work, it will rely on uncertainty in the mind of the potential aggressor. It was generally reckoned, in the days of the Cold War, that NATO would only be able to sustain a few days of conventional fighting before resorting to a tactical nuclear strike. It was hoped that this might cause the aggressor to pause before escalating. In his 2024 book ‘War’ Bob Woodward recounts a phone conversation on 26^th October 2022 between General Mark Milley Chairman of the Joint Chiefs of Staff, with his Russian counterpart, General Valery Gerasimov. The Russian doctrine then in force dated from June 2020, which meant that those speaking could be certain that there was no risk, at that time, of Russia using its nuclear weapons in relation to operations in Ukraine.

In November 2024, Putin updated this doctrine. A House of Commons Library research paper cites this new doctrine as:

• The new doctrine officially brings Belarus under the Russian nuclear umbrella.
• In changes to previous doctrine, the use of nuclear weapons would be justified against conventional aggression that poses a critical threat to Russian/Belarusian sovereignty and/or territorial integrity, as opposed to the very “existence of the state”.
• An aggression against Russia by any non-nuclear state with the participation, or support, of a nuclear state, would also be regarded as a joint attack on the Russian Federation

 

Comment

The rise of sub-threshold, so called Hybrid warfare, enables hostile states to undertake activities that are below the threshold of war-like action. It is also apparent from Putin’s activities in Ukraine, that Russia believed that the west would not respond to its attack in February 2022. This leads to the conclusion that the west (the UK and its allies) should ensure that conventional deterrent capability remains at the highest level and is sustained over time. There can be no ‘peace dividend’.

Western societies are vulnerable to disruption, which can cause dislocation and civil unrest if essential supplies are threatened. A means needs to be found to signal to hostile actors that their Hybrid actions, or those of their proxies, will have consequences. The importance of this lies in creating a resilient culture, which can resist coercion.

Looking to the future, nuclear deterrence will remain a necessity as long as nuclear weapons exist. The US, Russia, China, France and the UK all operate submarine based nuclear deterrent forces. Predictions that the sea will soon become transparent are speculative, although sensors positioned in the right place can assist in locating submarines. For the time being the submarine force will remain the ‘silent service’.

The sub-text of Thatcher’s speech in Moscow is that a nuclear free world is one that is safe for the sort of destruction that was seen in Chechnya, Syria and which is being seen in Ukraine today – only without limits.

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