Nuclear proliferation, irreversibility and the myth of ‘defence’

Tom Unterrainer

From END Info 43 | July 2025 | Download here

The British government’s plan to purchase 12 nuclear-capable F-35A jets from the United States quickly followed publication of the 2025 Strategic Defence Review. The Review itself only hinted at this possibility in ‘Recommendation 30’, which reads:

“30. The UK must facilitate greater coherence between conventional and nuclear components of NATO’s deterrence and defence posture ... Action should include:

... Commencing discussions with the United States and NATO on the potential benefits and feasibility of enhanced UK participation in NATO’s nuclear mission.”

[SDR, Page 102]

To date there has been little debate or deliberation in Britain’s democratic institutions on this announcement, though some probing questions were recently put in the House of Lords. Nevertheless, a deal has been struck with the Trump administration to purchase F-35A’s at an estimated cost of $80 million each with an expected delivery date of 2029. Each F-35A costs significantly less than the F-35B variant, which has the ability to perform short take-off-and-landing meaning it is suitable for aircraft carriers. The British government has reduced the number of F-35B’s it will buy, replacing them with 12 nuclear-capable, duel-use F-35A’s.

The total spend on the F-35A’s will be only one element of the total costs. For example, how much will it cost to staff and maintain these aircraft? The British government has not said. Further, the F-35A’s are specifically designed to carry and ‘deliver’ the new US B61-12 nuclear bombs. The SDR commits the UK to “enhanced participation in NATO’s nuclear mission.” How much will this cost? For instance, who is paying for the B61-12’s? Where will they be stored, at what cost and for how long? However, more than pounds and dollars are a stake in this announcement. Questions of proliferation, international law and the very concept of “defence” are in play.

“Ultimate guarantor”

Successive British governments have claimed that the submarine-based Trident nuclear weapon system is the “ultimate guarantor”of security. In his speech launching the SDR Prime Minister Starmer praised the ‘continuous at sea deterrence’ (CASD) operation, named Relentless, that has ‘kept us safe’ for decades.

In reality, CASD continues to be plagued with difficulties – not all of them the result of ageing, difficult-to-maintain Vanguard submarines. Yet CASD and the nuclear warheads aboard the submarines are regularly heralded as the dependable means by which the nation is defended.

If this is the case, then why the need for 12 US nuclear-capable F-35A aircraft and why the need for “discussions” on “enhanced UK participation in NATO’s nuclear mission”? Why, for the first time since 1998, does Britain need a second – air force – leg to its nuclear capabilities if it already has an “ultimate guarantor” of security?

In fact, nuclear weapons do not guarantee security and the development, proliferation and enhancement of nuclear capabilities is about power. Elements of this melding of nuclear capabilities and global power are clear in the very structures of Britain’s existing nuclear capabilities and in the nuclear-armed NATO Alliance. For the first element, it is widely known and well established that Britain is dependent on US assistance for existing, submarine-based nuclear weapons systems [see Bairns not bomb – John Ainslie dissects Trident, Spokesman 153]. In return, the US has access to a strategic North Atlantic harbour on the western edge of the Eurasian landmass and a pliant state at its disposal. For the second, Britain’s existing nuclear capabilities are assigned to NATO, which is itself ultimately under US command.

With this reality in mind, how to explain this most recent example of nuclear proliferation other than as a deal to further extend US – that is, the Trump regime’s – power? Was Britain’s agreement to become home to yet more US nuclear weapons part of the recent US-UK trade deal?

Irreversibility or Proliferation?

All nine known nuclear-armed states, including Israel, are actively involved in developing new nuclear weapon capabilities, either by technological development or – as with the current case of the UK – increasing nuclear warhead stocks. Actual nuclear proliferation within existing nuclear-armed states is a significant factor in international instability, acting alongside the potentially destabilising prospect of new nuclear-armed states. In fact, the contradiction at the heart of the Nuclear Non-Proliferation Treaty – official recognition of and legitimacy for nuclear armed states – in itself drives proliferation within nuclear-armed states and stretches non-proliferation frameworks to the point of ineffectiveness.

In an effort to ameliorate concerns over this contradiction, the nuclear-armed states pledge themselves to various additional measures within the NPT framework. For example in 2000, the Final Document of the Review Conference pledged member states to apply the ‘principle of irreversibility’ with respect to their Article VI commitments.

Article VI of the NPT commits member states to pursuing “negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.” In classical thermodynamics, the principle of irreversibility applies to a “process that cannot be undone.” In international law relating to nuclear weapons, the principle surely has a similar meaning, that is: if you dispense with an element or the entirety of your nuclear capabilities then you’re not permitted to have them back. A 2022 report, Irreversibility in Nuclear Disarmament, issued by Wilton Park in association with the British and Norwegian governments attempts a more ‘nuanced’ approach to agreements on irreversibility. For example, the report suggests that:

“Exploring forward-looking concepts like irreversibility may therefore seem premature or possibly even futile. However, there is clear utility in doing the preparatory work in anticipation of a more favourable strategic moment.”

This suggests agreement on irreversibility ‘in principle’ but that it will take effect at some future point. A more recent report – The Balance of Confidence and Feasibility in Irreversible Nuclear Disarmament (May 2025) – from the Vienna Center for Disarmament and Non-Proliferation argues that:

“the principle of irreversibility of nuclear disarmament is deeply ingrained in the international discourse, including in the context of the NPT.”

But that:

“the overwhelming majority of respondents adhere to the view of nuclear disarmament as a process rather than a fixed end state and pay greater attention to its procedural aspects than to defining a specific end state. One can conclude that the majority of States are prepared to address practical steps on an ad hoc basis, evaluating each step or activity as the process moves along until a degree of disarmament that can be characterised as sufficiently irreversible is reached.”

Whilst some NPT member states, the UK included, have recently paid attention to ‘irreversibility’ and reckon on its importance, there is acknowledgement that it does not yet apply to them. This curious attitude to ‘irreversibility’ exposes NPT member states to accusations of double standards. For instance, the Wilton Park report details some of the efforts made when North Korea withdrew from the NPT in 2003. The report points out that the US itself called for the “complete, verifiable, and irreversible dismantlement” of North Korea’s nascent capabilities. It is far from clear that the US itself adheres to ‘irreversibility’ or indeed any constraint of its own.

The charge of ‘double standards’ is more clearly posed in the case of the most recent UK-US nuclear deal. At the time of their ‘retirement’ in 1998, the UK possessed between 200 and 250 WE.177 free-fall nuclear gravity bombs. The previously-planned replacement weapon, an ‘air-to-surface’ missile, was cancelled in 1993. Writing in the Independent, Christopher Bellamy (‘Missile system ‘no longer needed’’, 18 October 1993) explained that of the £1.8bn earmarked for the missile system in 1993 (over £5bn in 2025) the:

“bulk of that expenditure would have fallen at the turn of the century, and continued after the last of the ageing WE.177 free-fall bombs it was due to replace had been scrapped in 2007.”

As things turned out, the WE.177 was scrapped in 1998. Bellamy offers some context for the decision to cancel the replacement weapons:

“Privately, MoD sources said that to have proceeded with a second new nuclear system, in the present international climate would have been ‘ridiculous’.”

To recap: the Conservative government of John Major announced the ‘retirement’ of the WE.177s by 2007. It then cancelled the planned replacement weapons. In 1995, the same government accelerated the ‘retirement’ of the WE.177s which went out of service in 1998, under the incoming Labour government of Tony Blair. Two successive governments oversaw and enacted the scrapping of a ‘second leg’ to the UK’s nuclear capabilities. They did so, to quote Bellamy again, on the understanding that:

“Trident ... is flexible and accurate enough to be used for a ‘limited nuclear strike’ – possibly with just one warhead per missile.”

If irreversibility commitments are to have any standing at all, then it is surely impermissible for the UK to replace the WE.177s two decades later with US B61-12s? Is this not a clear breach of the UK’s NPT commitments?

NATO

On 1 July 2025, the House of Lords – the unelected upper chamber of the UK parliament – debated ‘UK Weapon Systems’. This debate was notable because it included questions surrounding the ‘independence’ or otherwise of the UK’s nuclear capabilities. It was also highly informative, as it confirmed the actual conditions under which the UK’s commitment to purchase 12 F-35A nuclear-capable aircraft have been made.

The Lord Empey, former leader of the Ulster Unionist Party, opened with the following question:

“To ask His Majesty’s Government whether they have complete control over the use of all UK weapons systems without needing to consult, or seek approval from, other governments or third parties.”

Answering for the government, Lord Coaker – an unelected Minister of State for Defence – stated:

“His Majesty’s Government have complete control over the operational use of all the United Kingdom’s weapons systems, without needing to consult or gain approval from other Governments or third parties. This includes the nuclear deterrent.”

Undeterred, Lord Empey pressed on:

“... weapons systems require maintenance, and require to be renewed ... It is my understanding that not all of that process takes place in the United Kingdom ... Therefore, the question is: how independent is “independent”?”

Lord Coaker’s response:

“Well, “independent” means what it says ... We can use all our weapons systems in the way that His Majesty’s Government choose to. Of course there are arrangements about how you maintain that and what you do, but independence means independence ...”

When pressed further by Lord Wallace of Saltaire, with particular reference to the possibility that US warheads will be stationed at bases in Britain, Lord Coaker responded:

“... the fighter deterrent of the 12 F35A’s will require the authorisation of the United Kingdom Prime Minister.”

Baroness Goldie asked the next question, which finally prompted some clarity from the Defence Minister:

“Given the answer that the Minister has just given, can he clarify that, while it may very well be the case that at NATO level the Prime Minister of the United Kingdom would be required to give consent, is it conceivable that the United States in that scenario might refuse consent?”

Lord Coaker replied:

“Let us deal with this, and I apologise to the House if this takes some time. The strategic deterrent, CASD, remains, as we have always had it, operationally independent and a UK weapon. As for the 12 F35As that the Government have announced, that forms part of NATO’s nuclear mission. The F35As are UK jets and they are dual-capable aircraft, so they can be used normally or, in a particular crisis or a particular sense in which we felt and NATO felt that they should be used, they would become part of the nuclear mission. At that time, they would be armed with American nuclear missiles.

Of course, that means that the authorisation of the use of those missiles remains US-controlled, because, in the same way that we control our UK nuclear weapons, US nuclear weapons remain subject to US approval. The point I was making to the noble Lord is important. Of course, the authorisation for the use of those weapons within the context of a NATO mission has to be agreed by the NATO planning group and the UK is part of that. In that sense, the Prime Minister would have to authorise those UK planes being used to deliver that nuclear capability. I hope that is clear to the House and to the noble Baroness, because it is an important point for us to make with respect to the nuclear shield and the nuclear capability that this country has, and how it will work in practice.”

So there we have it: the actual purpose of the purchase of 12 F-35A aircraft is to supplement the existing deployment of US nuclear weapons in Europe under, we assume, existing ‘nuclear sharing’ arrangements.

Could such an arrangement be a ‘get-out clause’, mitigating possible breach of the UK’s alleged commitment to Article VI of the NPT? After all, NATO – of which the UK is a founder member – has not at any point reduced its nuclear sharing arrangements (WE.177s were not ‘shared’ with the UK by the US). The inclusion of the UK in such arrangements could therefore be interpreted as not breaching ‘irreversibility’ commitments.

But weren’t the WE.177s, as with other UK nuclear weapon capabilities, assigned to NATO? Could not the assignment of new capabilities be considered a breach of commitments? This, of course, is a question for politicians, diplomats and lawyers, but the statements from the British government and elsewhere clearly raise more general questions. What, exactly, is going on and why is it going on? What means – and what interests – are coming together to drive this proliferation? Why don’t the professed commitments to the NPT prevent this process? How does this development fit with the wider drive towards European remilitarization? What of ‘defence’

The recent decade has not been an auspicious one for non-proliferation, arms control and disarmament treaties. Notwithstanding the full-frontal rejection of nuclearism embodied in the Treaty on the Prohibition of Nuclear Weapons (see ‘TPNW Dossier’ in Spokesman 147), it is evident that the US in particular and her NATO allies seem determined to upend the ‘nuclear order’ – painstakingly established over decades – to their own advantage. How else to reconcile the destruction of the ABM Treaty, the INF Treaty, the JCPOA (‘Iran Deal’)? How else to explain the fate of ‘Open Skies’ and the likely end of New START?

This process intensified as the US held firm to an ‘America First’ international doctrine as the basis for US global dominance was drastically undermined by the rise of alternative centres of power, which held very different points of view. As NATO expanded and increasingly adopted ‘global’ intentions, treaty after treaty and agreement after agreement was shattered.

The UK’s recent SDR and commentary around it is frontloaded with a perspective that ‘things have changed’ and that the ‘situation is dangerous’. Such claims are used as justification for significantly increased military spending and for a ‘society-wide’ effort to confront the manifold dangers.

For those in power, this requires ever greater military spending and ever greater preparedness for war. This spending and these preparations are done in lockstep with the US and, for the time being, with the Trump regime. What they call ‘defence’ is reduced to even greater dependence on US power, its nuclear weapons and – as we have indicated – diminishing commitments to ‘international rules’.

Nuclear weapons defend nothing and risk everything. Recent developments risk further, potentially deadly, rounds of proliferation. The myth of ‘defence’ must be vigorously challenged.