By Air Marshal Greg Bagwell CB CBE

I recently posted a couple of threads on X, which raised the question of whether the UK’s current and planned replacement solution for its nuclear deterrent was sufficient for the nature of the threats we face today. Firstly, let me be crystal clear, deterrence is the watchword here, – no sane person wants a nuclear exchange or war to ever occur – regrettably today, that means ensuring that you convince an enemy that the cost of starting a nuclear exchange is far, far greater than any perceived benefit.

Many use the reference point of the Cold War to frame their understanding and the arguments for and against a nuclear deterrent – and many still view nuclear war through the lens of an intercontinental exchange of biblical proportions. Unfortunately, we now face a very different threat today, one without the same rules and understanding, but one that is far more volatile and just as dangerous. The Cold War was focused entirely on one threat – the Soviet Union – today, that threat includes China, North Korea and potentially soon Iran. Deterring multiple threats simultaneously makes the new challenge difficult enough. But in Russia we now see a regime that is openly flaunting international rules and law, with Putin almost cavalier in his attitude to using the threat of nuclear weapon use in the context of western support to Ukraine. The other countries mentioned are also increasingly exhibiting the same behaviours and are now colluding openly.

In addition to failing relations with these countries, we also see them growing and modernising their arsenal of nuclear weapons – especially in China. But most significantly, and most relevant to this article, we continue to see huge numbers of what are euphemistically termed tactical nuclear weapons – Russia alone has over 1500 of them. By tactical weapons, we mean those that can be employed on the battlefield, with a much lower yield than the weapons reserved for a strategic capability capable of inter-continental flight and more devastating results. The UK relies exclusively on the latter to deter the former.

Those who suggest that a nuclear war is so unthinkable and so terrible, immediately argue that this makes any use incomprehensible. But that belies the fact that that just the threat of their use has paralysed, or at best delayed, vital assistance to Ukraine. Indeed, you can’t have a debate about more support for Ukraine on social media without instantly being accused of wanting to start World War III – a view that appears to extend to the Pentagon and the White House. If ever you needed evidence of the practical impact of nuclear weapons on real World events, then that is the perfect example. The extra irony is that the illegal invasion of Ukraine can be traced back to the moment it gave up its nuclear arsenal for assurances of safety and protection.

So we need to rethink what all this means for how we deter Russia and others from acting against NATO and her allies in the future. Nuclear deterrent theory is an incredibly complex subject, but it does come down to the threat of counter use that makes any first strike too painful to contemplate. Even here theory does not stand still and Russia has only recently rewritten its nuclear doctrine to lower the threshold for the employment of its nuclear arsenal. Whilst much of this is to address its bungled situation in Ukraine, we should never ignore a nuclear armed state that starts to lower its threshold for their use.

In the UK, since the retirement of its airborne options in 1998, we rely on our Continuous at Sea Deterrence, provided by our magnificent submarine force on the Vanguard submarines. But recently we have seen how fragile that capability can be, with test firing failures, crew shortages, longer patrols and even a recent fire at our single manufacturing facility for its Dreadnought replacement. But perhaps just as serious is the fact that it is what is known as a strategic or ultimate response, to what is increasingly becoming a more nuanced, lower-threshold challenge. The US addresses this by maintaining a Triad of nuclear capabilities – ICBM silos, Submarines and nuclear bombers. Even in some NATO countries, US provided and controlled, air-delivered weapons are provided to countries such as Belgium, Germany, Netherlands and Italy in order to add some additional, more diverse options and an additional rung to the escalation ladder. And as we await the results of the imminent US election, we cannot ignore that as the threat broadens, and the US reconsider their priorities, European members of NATO might have to pick up greater responsibility in its own backyard. France has both air and sea-launched options and perhaps a model closer to our own – they certainly offer some opportunities for collaboration with MBDA being the producer of their airborne ASMP missile. France refer to their airborne tactical option as a “pre-strategic weapon” – effectively a warning shot before employing their more potent submarine launched missiles. As things stand, therefore, the UK stands out from all the nuclear powers (and even the European “borrowers”) as the only holder of a purely strategic option.

Whilst, I am a staunch believer – despite the huge costs to the defence budget of its replacement – in the Continuous at Sea Deterrence as our ultimate insurance policy, this Defence Review may be an opportunity to ask if that is robust or flexible enough to meet the evolving threats. There are options to restore our airborne capability, either through the already cleared, US-supplied F35A and B61bomb combination, or perhaps seek our own sovereign or European solution with a UK or French weapon on our future aircraft the Tempest. At the very least we need to have a conversation about a threat that some might have thought diminished after the Cold War, but is still very much a growing concern. Dual use aircraft (assuming we are buying something to meet the conventional requirement) such as the F35 or possibly Tempest, would mean that the costs and imposition of such a capability could be bounded.

Dual use means an aircraft capable of fulfilling a conventional and nuclear role. It does require some role-specific ancillaries for carriage, arming and release, but they are not prohibitive, nor should they interfere with or limit its conventional role. The management of the weapons themselves (and the aircraft when loaded) requires infrastructure that is secure and protected (hardened), and the security personnel to protect it. But dual use aircraft do not need to be maintained at very high readiness continuously when CASD is on task, and holding a readiness of days or weeks would have little impact on a force that could conduct the modest training required using dummy weapons and simulators. If and when a higher readiness was called for in times of increased tension or war, then a posture like the existing air defence QRA could be maintained at less than 15 minutes readiness, using just a single pilot and handful of groundcrew for each aircraft on task. Whilst this would then diminish the conventional capability commensurately, the situation would be grave enough to justify it.

To many, such a debate might seem pointless, unhelpful even, when Defence has so many other gaps to fill and seemingly not enough money with which to do it. Of course this in the context of our Dreadnought replacement swallowing up one third of the MoD’s equipment budget for the next 10 years. Indeed, if you remove the deterrent from the balance sheet, the UK would only be spending c1.75% of GDP on defence. But if the ongoing SDR is about two things: it is a laser-like focus on NATO first (but with a wary eye on China and others not far away), and a ruthless prioritisation on these things that deter any form of aggression or blackmail that could do us or our allies harm. With more countries acquiring more nuclear capability, and the threats now becoming multi polar we need to consider what this means for our deterrent posture and capability. We currently have a single basket with a finite number of eggs – although many would argue one is enough, especially when we are in a nuclear alliance. The UK is poised to spend a considerable sum of money in upgrading that basket, it would not do us too much harm to check and see if that policy covers all eventualities. The cost of making it even more robust and flexible may be a very small additional premium. The cost of us not deterring that threat doesn’t even bear thinking about.