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Strategic Defence Reviews (SDRs) have had a mixed track record over the last three decades. In some cases, they have rapidly been overtaken by geopolitical events, as with the reviews published in 1998 (followed two years later by the attacks of 9/11), in 2010 (followed two months later by the start of the Arab Spring), and in 2021 (followed within a year by the Russian invasion of Ukraine).
Reviews have also variously been criticised for being underfunded (1998), too constrained by funding considerations (2010), or for lacking detail on how the review will be funded and delivered (2015). Meanwhile, critics have repeatedly pointed to the gradual decline in the capability of the U.K. armed forces, evident over the course of repeated reviews that have reduced the quantity of equipment while seeking to outwardly position the armed forces as being capable and prepared on all fronts.
The 2025 SDR, published on 2 June, is undoubtedly a significant departure from its predecessors in many ways. It recognises that the world has changed dramatically and that radical reform of the Ministry of Defence (MOD), the armed forces, industry, and indeed the way that society views defence, are necessary in a very dangerous world. As far as it goes, this is a welcome approach, but the 2025 SDR must answer three key questions:
- Will it be overtaken by geopolitical events?
- Will it be funded?
- Can it be delivered?
Will it be overtaken by geopolitical events?
The publication of the SDR just a few weeks before the NATO summit in the Hague on 24-25 June makes this question particularly pertinent.
The SDR commits to a “NATO First” approach to deterrence and defence, with collective security underpinning the U.K.’s approach and with NATO at the centre of both force development and how the U.K. plans to fight in the Euro-Atlantic area. The approach recognises the centrality of NATO as well as the U.K.’s need to contribute more to the alliance while increasing its own resilience.
However, the SDR also recognises the “United States’ change in security priorities… [and that] fundamentally the U.K.’s longstanding assumptions about global power balances and structures are no longer certain”.
This lack of certainty has been all too apparent in European defence circles, since the speech by U.S. Vice President JD Vance at the Munich Security Conference in February 2025, in which he stated that internal threats were a greater danger to European security than China and Russia, followed soon afterwards by the meeting between Donald Trump and Volodymyr Zelensky in the Oval Office, which caused many to question the degree to which the U.S. would support its European partners and allies.
There has been much subsequent speculation as to whether the June NATO summit will see the U.S. significantly draw down its military presence in Europe, withdraw altogether, or even fundamentally call into question the existence of NATO. Any of these eventualities could undermine the fundamental assumptions underpinning the SDR. The U.K.’s emphasis on “NATO First” is grounded in its historical approach to Grand Strategy and it is undoubtedly in the interests of the U.K. to push for NATO’s continuing relevance. However, from the end of June, it may seem that in doing so the U.K. is swimming against a very strong tide.
Will it be funded?
Inevitably, the publication of an SDR shines a spotlight on levels of defence spending, resulting in calls for government to increase the percentage of GDP being committed to defence. Equally inevitably, ministers refuse to be drawn on the matter. Any defence spending aspirations beyond the current Parliament are just that – aspirations. However, SDRs must be grounded in financial realities, and if new and expensive capabilities are to be procured then they must be funded by cuts elsewhere or by increased taxes.
The SDR 2025 is undoubtedly ambitious in terms of its capability wish list, with high levels of spend required for nuclear warhead renewal, increased SSN attack submarines, munitions production, air and missile defence, the “Digital Targeting Web”, an increase in full time soldiers, and armed forces housing among many other new priorities. The government has committed to spending 2.5% of GDP on defence by 2027 and has an aspiration for this to increase to 3% in the next parliament – but, of course, it will not and cannot make a firm commitment to the latter.
Another important upcoming date is the publication of the Spending Review on 11 June. This will give us a firmer indication as to how much will be spent on defence vs. competing priorities, and how much headroom there may be for further growth of the defence budget.
Whatever the outcome of the Spending Review, though, the commitment to 2.5% of GDP is likely to soon make the U.K. appear as if it is lagging. European allies are committing to more, and many expect that at the NATO summit there will be a call to move to 3.5%.
The SDR leaves the difficult decisions about how to fund its wish list to the government and the MOD. It is silent on capabilities that will be cut (we may hear more in the Autumn, according to reports), and on the timing of many of its recommendations – some of which are explicitly for the next parliament.
However, the cost pressures within the defence budget have long been understood, with defence inflation typically significantly higher than CPI/RPI. This has been exacerbated in recent years by Covid-19, Russia’s invasion of Ukraine, efforts to increase military salaries and now, of course, tariffs. It may be that mechanisms for private investment (referenced in several instances in the SDR but without detail) can be used to address the MOD’s budgetary shortfalls – but any mechanisms put in place will need to avoid the pitfalls of the PFIs of the past. Funding an ambitious increase in capability without an equally ambitious increase in spending simply isn’t going to add up.
Can it be delivered?
Reading an SDR can be a bit like trying to read tea leaves. Pages that are, for the most part, high level can contain nuggets of information with potentially significant consequences – what, for example, are we to make of the phrase that “defence should commence discussions with the United States and NATO on the potential benefits and feasibility of enhanced U.K. participation in NATO’s nuclear mission”? Is this to be taken as an indication that the U.K. will acquire tactical nuclear capability? The SDR is otherwise silent on the issue, which would represent a very significant change to our defence posture.
Or, the Space chapter, which seemingly says very little until its last two sentences: “the MOD should seek partners to develop a next-generation, overhead, persistent intelligence, surveillance, and reconnaissance capability. This should provide the ability to sense, warn of, and track threats in the Euro-Atlantic”. If delivered, this would fill a major capability gap an area of current dependence on the U.S. However, it is addressed only briefly and lacks substantive detail, an issue that arguably characterises much of the document as a whole.
Historically, there have been legitimate reasons for SDRs to be light on detail. They are, after all, strategic documents rather than granular plans. The detail can be sensitive, and exists in underpinning classified documents.
This may have worked in an age, not so long ago, when the capability needs of the U.K. armed forces were met almost universally by a small number of Defence Primes who engage continuously with MOD at a working level and are a part of the “behind closed doors” discussions in which the capability needs are shaped. Today, the landscape is different, with new and disruptive players seeking to enter the market and to take greater risk by investing their own (or private investors’) money in product development. Indeed, the SDR itself calls for industry and private investors to take this risk on, and signals an intent to spend more with start-ups and SMEs. These newcomers to the defence sector have a lot to offer, but they struggle to navigate what can be a very opaque industry – and they need clear guidance from their target MOD customer.
Another upcoming event – the publication of the Defence Industrial Strategy (also thought to be coming up within the first two weeks of June) may shed additional light on how industry is expected to deliver the SDR. It is to be hoped that the DIS will contain further detail, but we are not convinced it will address all that’s lacking in the SDR.
As things stand, the MOD still has a lot of heavy lifting to do to turn the aspirations of the SDR – including radical and potentially game-changing procurement reform, the segmentation introduced and associated timelines – into reality rather than rhetoric.
