SDR: F-35As and tactical nukes for the RAF?

As is customary ahead of the UK’s Strategic Defence Review (SDR), select talking points were released to the country’s media outlets before the report was published. One article that was particularly striking was published by the Sunday Times on the 31st of May. “British fighter jets to carry nuclear bombs,” the title of the article declared, and proceeded to explain how the UK government was in high level talks with the US to procure F-35A jets, which are qualified to carry the B61-12 tactical nuclear bombs. The article added that:

“[Admiral Sir Tony] Radakin, who is stepping down as chief of the defence staff in the autumn, is said to view the expansion of the nuclear deterrent as the UK’s biggest defence priority and, in private, has long argued for air-launched capabilities.”

If this ambition is as far developed as the Times seems to imply, then it seems reasonable to assume that the UK, at some point, deploy jets that are capable of carrying US tactical nuclear weapons. However, there is a lot to consider around this development, especially from a military perspective – much of the public discussion has focused on the deterrent potential of the weapons, rather than their actual utility. And this is what this article will try and do. But first, what did the SDR actually say? 

The Strategic Defence Review on tactical nukes

“The SDR did not announce the expansion of the UK nuclear deterrent, nor did it specifically commit the UK to expanding its nuclear inventory with the procurement of an air-launched nuclear weapon capability.”

The above is taken from an informative report published by the House of Commons Library research team. The briefing appears to have been published in response to the article from the Sunday Times and straightens out several elements that might lead to confusion. The authors also point out that the SDR did recommend “discussions with the United States and NATO on the potential benefits and feasibility of enhanced UK participation in NATO’s nuclear mission.” 

The US shares some of its estimated 100 B61 and B61-12 tactical nuclear weapons with other NATO states, including Belgium, Germany, Italy, the Netherlands, and Turkey. Aircraft have to be certified to carry the bombs, which means that they can only be fitted to the Tornado, F-16, and F-35As, as well as the F-15s in US service. The UK’s F-35B fleet is not certified, and is also quite small, which presumably informs the recommendation that the future RAF fleet could “comprise a mix of F-35A and B models according to military requirements.”

However, it did provide extensive and ostensibly sound recommendations for the development of the service’s capability over the next decade, including a transition to a force with a much greater percentage of uncrewed and autonomous platforms, like the recently procured StormShroud. As mentioned above, more F-35s will be required, and it also recommends additional E-7 Wedgetails, an airborne early warning and control (AEW&C) aircraft designed to replace the E-3 Sentry. The UK initially ordered five E-7s, but reduced this to three in 2021, which meant that only would be available for operational tasking at any time. The project is also behind schedule, it was expected that the first E-7 would enter service in 2023, but is now unlikely to happen before December 2025. 

The review also recommends the augmentation of the RAF’s strategic carrier fleet, with either additional A400Ms or service agreements with commercial providers. Another aircraft order that the UK reduced, from an initial expectation of 25 to “at least 22,” in 2010. Further recommendations focus on the UK’s Protector UAVs, and suggests that they be provided with a maritime ISTAR capability to support the country’s P-8s and Type 26 ASW frigates, as well as a suite of remotely operated and autonomous ASW capabilities that were recommended to the Royal Navy. 

So far so good? 

Most of the recommendations are eminently sensible, providing that the Labour government is able to properly fund them. As noted in this Calibre Defence article, the UK’s nuclear enterprise alone is expected to cost £130 billion (€154.18 billion/$172.25 billion) in the next ten years, and there are many capability gaps that must be filled. One that is glaring, and does not seem to have been covered by the SDR, is the lack of strike capabilities for the UK’s Typhoon and F-35B fleets. It notes that both aircraft are a critical component of the UK’s integrated air and missile defence (IAMD) system, which is true, in fact they are arguably the majority of the UK’s IAMD capability. Even so, simulations have indicated that the UK would not fare well against a Russian cruise missile strike like the one directed against Ukraine on the 24th of February. However, the bigger question is in the following passage: 

“These platforms are also a key part of the IAMD offensive counter-air and deep precision strike capability that underpins conventional deterrence.” 

“Deep precision strike.” At present, the Typhoon is certified to carry StormShadow, which has proven itself to be very effective against Russia, albeit with a wealth of different enablers behind its use. The F-35B is not certified to carry StormShadow, nor can it carry the Spear 3, which MBDA developed specifically for internal carriage by the F-35 family. “The estimated current timeline for in-service capability [of Spear 3] is expected to be early 2030s,”  Maria Eagle, the Minister of State for Defence, told Parliament in May. This is understood to be related in part to the capability upgrades and improvements to the F-35, which are in turn dependent on developments in the US. The same delays also prevent the F-35B from firing the Meteor air-to-air missile, further degrading the RAF’s ability to contribute to the UK’s IAMD. The Typhoon could also carry Spear 3, and was actually used to test fire the missile in November 2024. But the UK MoD stated that there were no requirements or plans to fit frontline Typhoons with the weapon in November last year. 

Without Spear 3 or Meteor, there is very little that the UK’s F-35B fleet could contribute in the event of war with Russia. The stealth characteristics of the jets are very good against radar, but to deploy the Paveway IV guided bomb, they would likely have to come within visual range of a lot of Russian air defence systems. The Strategic Defence Review pays lip service to this dilemma, stating that investment in munitions is essential – which it is, and the Labour Government has committed £6 billion ($8.1 billion/€7.14 billion) to replenish its munitions stockpile, but this presumably includes the entire defence enterprise, which has spent many of its naval air defence missiles in the Red Sea, given most of its artillery ammunition to Ukraine, and is transitioning to a new form of tank ammunition that will render the existing stock useless. Even a modest procurement of missiles for the F-35 would consume a significant chunk of this funding – the US has placed more than $208 million (£153.92 million / €183.04 million) worth of orders for the Kongsberg Joint Strike Missile, for instance. That programme is only expected to provide a total of 268 missiles for the F-35. 

Armageddon for the brigade

Coming back to the nuclear question, how would tactical nuclear weapons fit into all of this? The B61-12 has a maximum yield of 50 kilotons, which is firmly a tactical weapon in terms of its effects. The website Nuke Map indicates that in an urban area, this blast would produce moderate blast damage out to a radius of 1.69 km as well as thermal radiation out to a radius of 2.87 km. The weapon is a gravity bomb, which can be delivered with some form of stand-off but not more than tens of kilometres, which means the F-35 would have to come very close to the target to deploy the weapon. As one colleague put it, this would be armageddon for the brigade that receives the strike, but not necessarily the world. It may lead to escalation and the use of much larger strategic nuclear payloads, which would be armageddon. But, in pure military terms, the use of tactical nuclear weapons is a contested issue. 

During the Cold War, tactical nuclear weapons formed a considerable part of both NATO and Warsaw Pact planning. They would be used to stop advances, leading to widespread contamination and presumed escalation. They also had an unintended consequence, which is that few seemed to assume war would last more than several weeks, and that nuclear escalation was inevitable. This created problems around wider preparation and industrial planning. If the Warsaw Pact had decided not to use nuclear weapons, for example, and fought a conventional war, it would have taken NATO countries some time to stand up their defence industry to support a prolonged and bloody conventional war. The Strategic Defence Review does well to emphasise the need for conventional weapons, but does not seem to fully address the glaring lack of capability within the RAF, and the focus on nuclear weapons appears to have caused some distraction. 

Calibre comment

This brings us neatly back to the Strategic Defence Review and its recommendations, the Sunday Times article, and the future of the RAF. Additional F-35As, A400Ms, E-7 Wedgetails, and autonomous combat capabilities should all be welcome recommendations. However, pursuing additional tactical nuclear capabilities, even if through collaboration with the US, would be a poor decision if it is taken at the expense of conventional munitions. The review repeats that it has taken lessons from Ukraine in its findings, but the war there should show more clearly than ever that magazine depth and industrial capacity are central to fighting and winning a war. Adding new platforms without procuring hundreds or thousands of missiles for them to use is a poor choice that will not contribute to security or deterrence. This should really be the focus of the RAF and the UK for the next three years, rather than attempts to buy in to the US tactical nuclear capabilities. 

By Sam Cranny-Evans, published on 4th June, 2025. The featured image shows a US F-35A carrying a B61-12 Joint Test Assembly. Two F-35A Lightning II aircraft released B61-12 Joint Test Assemblies during the first Full Weapon System Demonstration, completing the final flight test exercise of the nuclear design certification process. (US Air Force photo by Airman 1st Class Zachary Rufus)