UK Strategic Defence Review 2025

Long Awaited, Soon Forgotten?

The UK Government’s latest Strategic Defence Review (SDR 2025) was launched by Prime Minister Sir Keir Starmer in July 2024 and published by the UK Ministry of Defence almost one year later, on 2 June 2025.[1] There has been no shortage of expert and/or specialist commentary on the SDR since its publication. But reviews of public policy are a matter not just of what the reviewers meant it to say, but also of what its readership believes it says (or does not say). Accordingly, this essay asks how the SDR might be received and understood by a non-specialist, general public readership.[2]

In Defence of Nonsense

In the Times newspaper of 22 March 2025, a ‘Whitehall source’ was quoted as saying of the (then forthcoming) UK strategic defence review: ‘It is ambitious, forward-leaning, and to suggest anything else is nonsense.’ Attempts to steer and even stifle objective analysis of SDR 2025 continued up to and after its publication. In the spirit of open, impartial commentary on public policy, and at the risk of being labelled a member of the ‘reactionariat’[3], or even worse, here are some nonsense suggestions:

· SDR 2025 is so over-ambitious and under-committed that much of it will not be achieved.

· SDR 2025 leans more backwards than forwards, seeking (rightly) to bring UK defence to a position it should have been in a decade or more ago.

· SDR 2025 is future-oriented only insofar as it hopes that for the next ten years or so the future will behave itself, allowing the UK to catch up with 2025.

What can fairly be said of SDR 2025 is that it offers a critique that is both necessary and welcome. It is also ruthless: rarely have defence reviews been so candid and forthright in their assessment of the state of UK defence. But how much should be expected of the review? It is plainly about the geostrategic context and the mechanisms of UK national strategy – and very valuably so. But if strategy is also about devising a strong and durable link between ends, ways and means, as the basis for decision and action, durable for an uncertain future, to what extent is SDR 2025 as ‘genuinely strategic’ as its authors claim? What has been decided? What will be done, and when?

If national strategy is also a matter of public policy, will the UK public, who pay for national strategy in more ways than one, find in SDR 2025 a rounded, well-reasoned and persuasive account of how the UK will defend itself and its interests in the increasingly turbulent global security environment it describes? Will the public understand that for all the effort and analysis that has gone into it, SDR 2025 is largely advisory; that it is more of a semi-official scoping study, a ‘Plan for Change for Defence’, than a fully-fledged strategic commitment, for which we must wait until the publication of a National Security Strategy and other policy papers? And will public opinion welcome the fact that the widely called for increase in UK defence spending to 3.0 per cent of GDP is described as an ambition that will not be met until the 2030s (NB a decade rather than a deadline) and, even then, only if ‘economic and fiscal conditions allow.’ Tellingly perhaps, the word ‘ambition’ appears no fewer than ten times in the SDR, in relation to defence spending, the ‘Plan for Change’ itself, industrial collaboration with partner countries, the size of UK Cadet Forces, the delivery of ‘conventional deep strike capabilities’ and the lethality of the British Army.

Out with the Old

Gone from the ‘narrative’ of UK defence is the facile twaddle offered in recent views – particularly the ‘tilt’ to the Indo-Pacific and the notion of ‘Global Britain’. Previous discursions on the theme of strategic outreach have been replaced with a simple ‘new ambition’ to adopt a ‘NATO First’ outlook. For those with a working memory of the latter half of the twentieth century this new ambition might seem both familiar and self-evident. But ‘NATO First’ will not mean ‘NATO-only’; wary, perhaps, of over-correcting from past errors, SDR 2025 accepts that the Middle East and the Indo-Pacific also matter. And allies are vital, wherever they are.

Having recently made a brief appearance in the official lexicon, the ‘rules-based international system’ (RBIS) has been dropped from the bench in favour of the tried and tested ‘rules-based international order’ (RBIO). Sadly, no explanation is offered for this temporary substitution, nor for the fact that several non-western governments appear to take deep exception to both. As far as the UK force posture is concerned, noticeably absent is the prediction that the SDR might make the case for (yet more) very large cuts to the British Army. Some of the defence gobbledegook that infected recent reviews has, thankfully, also been dropped. Although not all. ‘Hybrid’ and ‘sub-threshold’ remain as echoes of past attempts to summarise the entirety of international security in just a PowerPoint-friendly word or two, yet with questionable results: ‘hybrid’ suggests offspring of very doubtful heritage and ‘sub-threshold’ implies more clarity than actually exists in our classification of war. That said, SDR 2025 does a much better job than past efforts simply by describing the strategic context fully and accurately – using words and sentences that are mostly intelligible. It also, largely, avoids the pictorial padding that plagued earlier defence reviews.

In with the New (-ish)

The SDR offers a concise account of the strategic context, out to 2040, in which the UK must operate. Much of this material will be familiar: the significance of novel and emerging technologies, the evolution of the threat landscape away from the relatively straightforward Cold War model of inter-state tension, threats of espionage, cyber attacks and so on. Although this description of the strategic challenges to the UK contains little that is new, the breadth and variety of these challenges should be salutary. By way of response, the SDR calls for a wave of approaches, packages, personnel redeployments, policy redesigns, plans, pathways and reviews to be initiated and completed in a month by month tempo over the coming year or two. The document contains no fewer than 62 recommendations, all of which have been accepted by government and are to be implemented. It is of course one thing to ‘accept’ a recommendation, another to turn recommendation into ‘decision’ and entirely another to set a date by which that decision will take effect. Nevertheless, the fact that so many initiatives are deemed necessary emphasises, once again, just how unimpressive UK defence has been allowed to become and might give some hope that things could now begin to improve.

The review argues for the restructuring of UK defence into four areas: the Department of State, the National Armaments Director Group, the Military Strategic Headquarters and the Defence Nuclear Organisation. The purpose of this wave of organisational reform is clear: ‘to establish robust and streamlined governance, clearer accountabilities, and faster decision-making processes across the Ministry of Defence and the Armed Forces.’ Given years, if not decades of belittling criticism of the MoD in Parliament and the media, many readers will welcome these reforms as both timely and essential, although some with longer memories might also experience a very strong sense of déjà vu. Some might wonder whether the MSHQ will ever be able to do what is expected of it – can any senior officer, with his or her single service background, ever really be ‘in formal command’ of all three services as well as Strategic Command? The procurement of military equipment is singled out for reform, although the case for doing so is probably as obvious and urgent now as it has been for decades. The ‘more intelligent approach’ to defence acquisition seems remarkably similar to previous ‘more intelligent’ approaches and the replacement of the Defence Equipment Plan with a (ten year) Defence Investment Plan has all the appearance of a distinction without a difference, while evoking images of deck chairs being rearranged on the Titanic. At the heart of the new relationship between MoD and defence industry will be a ‘segmented approach to procurement’. This is a neat and easily comprehensible idea although it remains to be seen how a complex process such as defence acquisition can be simultaneously ‘segmented’ and ‘integrated’ (i.e., based on the 2024 Integrated Procurement Model).

SDR 2025 calls repeatedly for a ‘whole-of-society’ approach to deterrence and defence, with a view to ‘widening participation in national resilience and renewing the Nation’s contract with those who serve.’ Arguably one of the most interesting and important aspects of the SDR, this idea, although not new, is very much to be welcomed. It would, however, amount to a fundamental shift in the UK’s strategic culture (a term that is used just once in the SDR, and only in the narrowest sense). It will require sophisticated thought leadership if it is to succeed and will range far beyond the competences of the Ministry of Defence. What is most obviously within the scope of the MoD is the Armed Forces Covenant. This should surely be an element of the ‘whole-of-society’ approach and it is surprising that this initiative is mentioned nowhere in the SDR. Resilience, on the other hand, is mentioned very many times. Here too, some discussion of the precise meaning of the term would have been welcome. And it might also be useful to note that UK government has undertaken a great deal of first class work on this theme over the past two decades.

The tone of SDR 2025 is more urgent and impatient than its predecessors, and sometimes awkwardly so. Readers are informed on several occasions that ‘‘business as usual’ is no longer an option’ and that ‘the time for action is now’. While the sentiment behind this language is not unreasonable, some in and around government might find the choice of words to be too much of a contrast with the nuanced way in which public policy is usually presented and might consequently dismiss SDR 2025 as too ‘gung ho’ and blimpish to be taken seriously. The final novelty worthy of note is the inclusion of banal comments made by members of something called a ‘Citizens’ Panel’. These might also raise the odd eyebrow. Does a mature and sophisticated strategic defence review really need to patronise its readers by including such observations as ‘We do need to put more into our defence because otherwise it won’t be long before something more significant happens and we will think it should’ve been more of a priority’?

UK Armed Forces

The underlying goal of SDR 2025 is to produce military forces that are ‘fit for war in the 21^st century.’ To that end, the document declares an ambition (that word again) to move to ‘warfighting readiness’. Some might wonder whether this should always have been the core function of the Armed Forces and whether the mere ‘ambition’ to restore that capacity is sufficient. In this respect the SDR fails to draw the conclusion made obvious by its own analysis: ‘the MOD does not control the timetable for confrontation and conflict. “Events” and the UK’s adversaries do.’ If this is the case (and I would say that it certainly is) then why does SDR 2025 (NB ‘the time for action is now’) allow another ten years or so for preparation?

If the UK is indeed preparing itself to achieve ‘warfighting readiness’ then the reader of SDR 2025 might expect to find very detailed information on the configuration and strength of UK military forces, as well as a clear sense of the UK’s strategic/military priorities. But the document is strangely thin on such detail. SDR 2025 lists several projects for ‘immediate action’ including the (old) news that the UK will build its own new nuclear warhead and will create a ‘New Hybrid Navy’, a British Army that is ten times more lethal and a ‘next-generation’ Royal Air Force. Other items on the list of aspirations include the development of an air and missile defence system for the UK, an increase in the attack submarine fleet, the production of ‘up to’ 7,000 new long-range weapons and the transformation of the UK’s two aircraft carriers into ‘the first European hybrid air wings’.

The three traditional services (described as the maritime, land and air ‘domains’) are covered, albeit with remarkably little information, as sub-sections of chapter seven entitled ‘The Integrated Force: A Force Fit for War in the 21^st Century.’ By combining mass and technology more intelligently and effectively, the integration of UK Armed Forces (another idea familiar to avid followers of UK defence reviews) will mean that by 2035 (or sooner ‘if circumstances demand it and should more resources be made available’) the UK will be a ‘leading tech-enabled defence power, with an Integrated Force that deters, fights, and wins through constant innovation at wartime pace’. Force integration has long been a compelling idea in UK defence but at the strategic level it has also proved difficult to achieve. That experience might explain why, although 2035 is floated as the target date (ensuring that UK Armed Forces will be effective at least for the latter two thirds of the 21^st century), the Integrated Force will have no ‘fixed force design to be delivered by a specified date’; ‘there is no end state for the Integrated Force: its design and capabilities – and the way that wider Defence supports it – must continue to evolve as threats and technology do.’ A more serious question now arises. How will it be possible to ‘undertake an annual evaluation of the effectiveness of the Integrated Force model’ called for in the SDR; against what standards and expectations? And how can the results of these annual evaluations be trusted? The same question should be asked of the SDR’s aspirations to achieve a more lethal Army, a more productive defence industry and a more significant economic spill-over from defence spending. The SDR admits, rather alarmingly, that the MOD has yet to ‘establish and track metrics’ for all three of these goals. SDR 2025 also promises that the Integrated Force will be served by ‘constant innovation at wartime pace’. This is not realistic. What makes innovation at ‘wartime pace’ possible is, surely, because there is a war underway. Yet the reader is repeatedly informed that SDR 2025 is about becoming ‘better prepared for high-intensity, protracted war’ rather than actually fighting one (a least not yet). It is simply not possible, even for the UK, to be simultaneously at peace and participating in a major war.

The Integrated Force also embraces the UK’ nuclear deterrent – ‘the bedrock of the UK’s defence and the cornerstone of its commitment to NATO and global security.’ But what is behind the recommendation that discussions should begin with the United States and NATO on ‘the potential benefits and feasibility of enhanced UK participation in NATO’s nuclear mission’? What does ‘enhanced participation’ mean? As was suggested in a Sunday Times article appearing shortly before publication of the SDR, does this vague language hint at the possibility of a ‘new layer’ (e.g., aircraft-launched nuclear weapons) being added to the UK’s nuclear inventory? If the UK’s strategic nuclear posture is being reconsidered, should this not have been discussed in a strategic review? Or did an arms control specialist in the FCDO make the awkward observation that ‘vertical proliferation’, as it is known, might send signals to near-nuclear powers that should probably not be sent? SDR 2025 certainly does seem oblivious to the problem of contradictory messaging where nuclear arsenals are concerned. Nuclear weapons are presented as the ‘bedrock’ of UK strategy yet China and Russia are implicitly to be vilified for ‘putting nuclear weapons at the centre of their security strategies.’ Is it possible that near-nuclear powers might detect double standards at work?

Last Words

The UK is beginning its defence recovery from an alarmingly low, and unimpressive level of national military capability. Although there are discussions to be had about many aspects of SDR 2025 the document does at least serve to describe the dismal present and to suggest ways out of it. But if recovery is to be delayed still further, or to be shaped by the imperative of limiting defence’s burden on the public finances, then the candour of SDR 2025 might over time have effects opposite from those intended. Will the UK public be so alarmed by what is depicted in the SDR that support for the Armed Forces will diminish rather than grow? After all, who would wish their taxes to be spent on something so apparently deficient? And who would willingly be recruited to join an organisation that might not have sorted itself out for another decade or so? What will allies think? Will NATO governments insist that the UK can no longer present itself as a leading player in the Alliance without spending considerably more on defence than is currently scheduled? And will adversaries be convinced that the UK’s Armed Forces have the deterrent and fighting strength that is claimed?

Is the UK government willing and committed to paying for the recovery of UK defence in the immediate future, and with no strings attached? And how will any such commitment be measured – in terms of a per centage of GDP spent on defence (a measure of fiscal input) or in terms of military capability (a measure of strategic output)?[4] In February 2025 Prime Minister Starmer announced that the 2024 manifesto commitment to spend 2.5 per cent GDP on defence would be brought forward to 2027, with a further increase to 3.0 per cent GDP, as reported in SDR 2025, ‘when fiscal and economic conditions allow’. As an interim measure, in late March 2025 Chancellor of the Exchequer Reeves announced a £2.2bn boost to defence spending that would increase UK defence spending to 2.35% GDP in FY 2025-26. Published on 11 June 2025, the UK government’s latest Spending Review – in which departmental budgets are set for the next five years – increases the 2027 target from 2.5 to 2.6 per cent GDP and maintains the 3.0 per cent/2030 input aspiration, hedged in the same way.[5] While some important spending commitments have been made (nuclear warhead, directed energy weapons, autonomous systems, munitions manufacturing and infrastructure) decisions as to the size, shape and capability of UK Armed Forces will not be made until the Defence Investment Plan is published later in 2025. In other words, in spite of the unimpressive state to which UK Armed Forces have sunk, in spite of the mounting pressure from allies, in spite of the war in Europe and in spite of the worryingly unstable international environment, the UK proposes an approach to national strategy that is as long term and as parsimonious as ever; its own version, in effect, of the ‘business as usual’ approach rightly criticised in SDR 2025. And there will indeed be strings attached to defence expenditure in the form of the Prime Minister’s ‘defence dividend’ that the government is ‘determined to seize’. This could prove to be a disastrously short-sighted way of measuring the value of spending in defence. The purpose of defence spending is not to produce a financial dividend of some sort. Of course, public spending should create opportunities in employment, innovation and so forth. And it is not unreasonable to expect that public spending will have multiplier effects in the wider national economy. But this cannot be the purpose of defence, any more than it can be the purpose of spending on health or education. Defence and deterrence are a necessity, spending on which must be justified first and foremost as an essential national cost, not as the route to a marginal benefit of some sort.

Strategy must, inevitably, be shaped by domestic politics and by the vitality of the national economy. But strategy should not be about either of these things. Like all strategy, a strategic defence review should be rooted in the past, active in the present but fundamentally about the future. And the future is mobile: it never remains where it was first spotted and it has the disturbing habit of becoming the present sooner than might be hoped. The test of an effective and durable defence review is whether government can show itself, credibly and convincingly, to be able to deal with an area of public policy that is prospective, contingent and in competition with other national priorities.

SDR 2025 will be soon forgotten. Although it offers some sophisticated and provocative analysis it will be forgotten because it does not do what is expected of it and it will, in any case, be overtaken by other policy announcements. A strategic defence review should not read like a party political, pre-election manifesto; full of ideas and commitments that might (or might not) be met. If readers expect a strategic defence review to be more concerned with decision than analysis then, no matter how good the analysis and how compelling the conclusions drawn from it, they will be disappointed. Similarly, if readers expect a strategic defence review to be largely about UK Armed Forces – their shape and size, what they might be required to do, where and when, and how they will be equipped – then they might be even more disappointed by a document that seems to go out of its way to avoid such detail. What is left is a (rather good) review of the state of international security alongside a (rather timely) review of the management, procurement and spending procedures of the UK Ministry of Defence. Although both are worth reading, for the purposes of national strategy they are not enough. Public policy documents must, to some extent, be performative. But SDR 2025 is a performance without a coherent strategic plot. Equally, national strategy documents must be speculative – they are after all concerned with the future about which little, if anything, can be known. But SDR 2025 is speculative in the two areas of national strategy in which it should be anything but tentative – political resolve and economic commitment. On balance, I suspect a general readership (as well, perhaps, as some generals) might not find SDR 2025 to be a work of strategic genius. Might it, at least, be considered a work of strategic competence? With so much follow-up work to be done, and with so many implementing decisions yet to be made, it is not yet possible to answer this question, suggesting that SDR 2025 might not qualify as ‘strategic’ at all.

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[1] Ministry of Defence, Strategic Defence Review. Making Britain Safer: secure at home, strong abroad (UK Ministry of Defence, 2 June 2025): https://www.gov.uk/official-documents

[2] Paul Cornish is director of the Centre for the Public Understanding of Defence and Security at the University of Exeter: https://www.exeter.ac.uk/research/networks/policy/ourwork/cpuds/

[3] See Keith Dear, ‘UK Strategic Defence Review (SDR): Reviewing the Review & the Reactionariat’ (Substack, 4 June 2025):

UK Strategic Defence Review (SDR): Reviewing the Review & the Reactionariat.

[4] I have long argued that the ‘per centage GDP’ approach to defence spending is fundamentally non-strategic. See my Substack essay, ‘UK Strategic Defence Review 2025: L’Attaque versus Monopoly’, 13 December 2024: https://paulcornish.substack.com/p/uk-strategic-defence-review-2025

[5] HM Treasury, Spending Review 2025 (CP 1336, June 2025): https://assets.publishing.service.gov.uk/media/6849171796e63bce58e4e705/E03349913_HMT_Spending_Review_June_2025_Elay.pdf