Britain is missing a rung on the nuclear ladder

Peter Watkins knows the inside of Britain’s defence establishment better than most. As a Director General at the Ministry of Defence from 2014 to 2018, he was responsible for strategic policy, deterrence and defence industrial policy matters.

So when he co-authors a report arguing that Britain’s nuclear posture needs refreshing, it is probably worth paying attention.

The report, Rebuilding the Ladder: Options for Boosting Britain’s Nuclear Posture, was published in late April by the Council on Geostrategy, where Watkins is an Honorary Fellow. He wrote it alongside William Freer, the Council’s Research Fellow in National Security. Its central argument is that the UK’s current deterrent posture, built around a single submarine on continuous patrol, was designed for a world that no longer exists, and that Britain is missing a critical “rung” on the escalatory ladder, potentially leaving decision-makers with starkly limited choices in an escalating crisis.

We sat down with Watkins to talk through what the report found and what he thinks needs to happen. The first thing he wanted to get on the record is that none of this is a dig at Trident. “We’re not decrying Trident in any way as a strategic deterrent,” he says. “It’s very formidable, and it’s credible in the current strategic circumstances as a deterrent against the most extreme threats.” The problem, as he sees it, is that the world has moved considerably since the key decisions underpinning the current posture were made in the 1980s and 1990s.

Before Britain retired its airborne sub-strategic nuclear capability in the late 1990s, “that was an announcement that was made when the then government said it wouldn’t replace our then airborne sub-strategic capability,” Watkins explains. The claim that Trident could cover that role has never really been tested, and he questions whether it holds up. “If you’re launching a ballistic missile, how is your adversary supposed to know whether it’s a strategic or a sub-strategic strike? You risk escalating a crisis in a way that you didn’t want to.” There is also the question of what using Trident in that way would do to its primary purpose. “It is our secure second-strike capability, and if we use it in a sub-strategic mode, we risk compromising its position so it becomes less credible in its primary role.”

What about conventional deep precision strike systems as an alternative sub-strategic capability? The report rebuts the idea, and Watkins explains why. He acknowledges that conventional weapons have proven devastating in recent conflicts, but notes that their use in both Ukraine and Iran were in situations where air defences had already been largely dismantled, which is a rather different proposition to facing Russia. “Deterrence depends upon your adversary believing that you can impose costs on him that are much greater than anything he’ll gain by an attack, and we’re not convinced that conventional systems, however sophisticated, could ever be able to impose that degree of damage.”

Russia is never far from the surface in this conversation. The Kremlin has updated its nuclear doctrine, expanded its sub-strategic arsenal to nearly 1,500 warheads, and shown a willingness to treat nuclear weapons as tools of warfighting in a way that Western nations have not. Watkins draws a pointed contrast between the two sides. “Our nuclear doctrine is very clear at the moment, we would only use nuclear weapons in the most extreme circumstances of self defence. If you look at Russian nuclear doctrine, they seem to envisage using nuclear weapons to bring about war termination on acceptable terms. They seem to see nuclear weapons as integrated in war fighting in a way that we traditionally have not done.” Beyond doctrine, he says, the investment tells its own story. “If you look at what they’ve invested in, a massive arsenal of non-strategic dual-capable systems, Kalibr, Iskander and so on, one is concerned that they may envisage using nuclear weapons in circumstances that we never would, and therefore we need to have the full capability to deter them from thinking that way.”

So what should Britain actually do? Watkins outlines a programme running across the short, medium and long term. In the near term, he points to deepening cooperation with France, noting that British officials were permitted to observe France’s “Poker” nuclear exercises for the first time in December 2025, and that there is considerably more that could be built on from there. He is realistic about the limits of what Paris will agree to given the sovereignty France attaches to its deterrent, but thinks the framework for progress is there. “Both the President and the Prime Minister signed the Northwood Declaration back in July, so I think the French are committed to working more closely with the UK. There are going to be some limits, but I think even within the constraints of both countries having sovereign capabilities and ultimately independent decision making, there is scope for closer coordination.”

He also wants to see Britain’s public-facing nuclear doctrine updated, something that has barely changed in thirty years, and better nuclear education across the MoD, which he describes as currently quite siloed. On the question of public engagement more broadly, he points to France as a model, where it has become standard practice for presidents to make periodic speeches on nuclear posture and doctrine. “The government here doesn’t talk very much about our nuclear capability. In France it’s become a practice that every president, about every four to five years, will make a speech about French nuclear capability, doctrine and capability. We think something like that would be good.” He is careful to add that this is not about rattling sabres. “We’re not arguing that we should move to a Russian type posture of celebrating nukes and making extreme statements about them, it’s just a higher profile than we’ve had so far.”

On F-35As, the report calls for up to 24 more aircraft in the nuclear-capable A variant beyond the 12 currently committed. Watkins pushes back on the idea that this is simply a call to spend more money. “We’re not necessarily arguing here for spending more money. What we’re saying is that of the UK’s total envisaged F-35 fleet of 75 aircraft committed, more should be in the A variant.” He adds that the current plan of a single double-hatted unit covering both nuclear strike and pilot training looks too limited.

The long-term centrepiece of the report is a recommendation to develop a sovereign air-launched sub-strategic nuclear weapon, something Britain has not had since the retirement of the WE.177 in the late 1990s. The report puts the cost at somewhere in the region of £11 to £14 billion over 20 years, though Watkins argues the figure could be brought down significantly by avoiding unnecessary complexity and adapting existing warhead designs rather than starting from scratch. The Atomic Weapons Establishment’s capacity to take on that additional burden is a real constraint, he acknowledges, but not an insurmountable one. “For the last umpteen years, AWE’s capacity has been sized around maintaining and developing one strategic warhead. They’re doing a huge amount of work down there. It is a challenge, but I would say it’s not an impossible challenge.”

Towards the end of our conversation, Watkins is measured but pointed about timelines. The short-term steps he has described, deeper French cooperation, updated doctrine, better nuclear education within the MoD, are all things he says could be done relatively quickly and without significant cost. “None of that should cost a lot of money or be that complicated.” On F-35As, he thinks the government should look seriously at whether the delivery of the first nuclear-certified aircraft, currently planned for the early 2030s, could be brought forward. “I think it would be good if they could accelerate that, and it’s not obvious to me why they couldn’t.”

The Defence Investment Plan, he notes, will be the first real indication of whether any of this is actually going to happen. Given how long that document has been promised, the wait continues.