Strategic defence review 2025

Approximate read time: 40 minutes

1. Background: Launch of the review, the defence reform programme, and defence spending

1.1 Launch of the strategic defence review and its remit

The Labour government commissioned the strategic defence review (SDR) shortly after taking office in July 2024—fulfilling a manifesto commitment to do so—in order to “consider the threats Britain faces, the capabilities needed to meet them, the state of UK armed forces and the resources available”.^[1]

The defence secretary, John Healey, described this SDR as the “first of its kind in the UK” because it was externally led, whereas previous defence reviews have been conducted by the government. The SDR was conducted by Lord Robertson, a former Labour defence secretary and secretary general of NATO. Lord Robertson was supported by two external reviewers, Dr Fiona Hill, former deputy assistant to the US president and senior director for European and Russian affairs on President Donald Trump’s National Security Council from 2017 to 2019, and General Sir Richard Barrons, a former commander of the Joint Forces Command and former deputy chief of the defence staff.

The Ministry of Defence (MOD) set out parameters for the review.^[2] The SDR’s terms of reference said that it would “consider the need for prioritisation of objectives, and therefore investments and activity, to set out a deliverable and affordable plan for defence”. The parameters were as follows:

• a total commitment to the UK’s nuclear deterrent
• a ‘NATO-first’ defence policy
• options to reinforce homeland security
• ongoing support for Ukraine
• the centrality of personnel to defence plans
• maintaining defence ties with the Indo-Pacific region, the Gulf and the Middle East
• a commitment to AUKUS, the partnership with Australia and the US to deliver new submarines and collaborate on emerging technologies

The review also sought external views. During the review process, 1,700 individuals, political parties, and organisations submitted around 8,000 responses, 200 companies provided written contributions, over 150 senior experts took part in the review and challenge panels, and around 50 meetings took place between the reviewers and senior military figures. Members of the public also toured defence sites as part of a ‘citizens’ panel’ to offer their views.^[3]

The review reported on 2 June 2025.^[4] Its key conclusions and recommendations are outlined in section 2 of this briefing. The remainder of this section will outline other key defence initiatives launched prior to the SDR report to put the review’s conclusions into further context.

1.2 Other key defence initiatives including the defence reform programme

Alongside the SDR process, the Labour government also launched the defence reform programme, which it described as “the deepest defence reforms for 50 years to fix what the [House of Commons] Public Accounts Committee calls the ‘broken’ defence procurement system and to strengthen UK defence”.^[5]

The government has announced several reforms pursuant to these aims, including the creation of a new national armaments director role. The government has said the aim of the post and wider procurement reform was to “ensure the armed forces are properly equipped to defend Britain, to build up the British defence industry and to crack down on waste”.^[6]

The new national armaments director will be responsible for:

• delivering the capabilities required from industry to execute the defence plans and operations demanded by the new era
• shaping and delivering the ‘Defence industrial strategy’
• ensuring a resilient supply chain and the required readiness of the national ‘arsenal’
• leading on UK defence exports and acquisition reform
• harmonising procurement and working closely with wider government, industry, academia, and international partners to deploy best practice and investment

At the time of writing, recruitment for the position was ongoing. The acting national armaments director is Andy Smart, who was appointed chief executive officer of defence equipment and support in the MOD in September 2022.^[7]

In addition, the government has also established a new military strategic headquarters and given new powers to the chief of the defence staff (CDS) to command the service chiefs for the first time.^[8] Ministers have said the CDS will now be central to investment decisions between the services, along with the defence secretary and permanent secretary. The government have also replaced 10 budget holders with four new budget areas for “tighter budget control”.

The government set out the details of its new leadership “quad”—the permanent secretary, chief of the defence staff, national armaments director, and chief of Defence Nuclear—in a statement in April 2025, and also spelled out wider organisational reforms:

The key features of our new system will be:

1. The permanent secretary will lead a more agile department of state. In line with wider civil service reform, this area will be lean and highly skilled, unleashing the exceptional capabilities within defence by making the systems and processes around us more efficient and empowering. This area will be responsible for providing policy muscle and clear strategic direction to ensure that the defence is focused on outcomes and delivery. The department of state will contain a streamlined set of four director general roles reporting to the permanent secretary, focused on strategy and transformation, people, policy and finance.
2. Our armed forces show great courage and collaboration in the work they do on operations to keep our country secure at home and strong abroad. The UK armed forces’ most senior officer, the chief of the defence staff (CDS), will, for the first time since this role was created, now command the service chiefs and head a newly-established military strategic headquarters (MSHQ) as the single point of force design and delivery of the armed forces. The new MSHQ will support the journey from a ‘joint’ to an ‘integrated’ force that better harnesses all five domains of maritime, air, land, cyber and space. They will be supported by a small central team integrating across activity and force design, prioritising investment to improve warfighting readiness and lethality.
3. The National Armaments Director Group will fix the broken procurement system and make defence an engine for economic growth in every corner of the UK. It will bring together teams delivering the national ‘arsenal’, the government’s ‘Defence industrial strategy’ and end to end acquisition under one leader, the national armaments director. This new structure will enable collaboration by bringing together Defence Equipment and Support, the Defence Infrastructure Organisation, the Defence Science and Technology Laboratory, Defence Digital and parts of Defence Support. The group will also include roles focused on international collaboration and exports, commercial and industry, options and commissioning, and corporate, with the Enterprise CIO moving to the group by 1 July 2025. These roles will work together, and with industry, academia, international partners and allies to develop and deliver innovative solutions to departmental problems.
4. The chief of Defence Nuclear (CDN) is responsible for cohering across the Defence Nuclear Enterprise (DNE), in addition to leading the Defence Nuclear Organisation (DNO) and its arms-length bodies. The DNE unites the Royal Navy, strategic command and DNO, with its ALBs including the Submarine Delivery Agency and Atomic Weapons Establishment—the partnership of organisations that maintain, renew, and sustain the UK’s nuclear deterrent which keeps us and our NATO allies safe 24/7. The financial nuclear ringfence ensures nuclear spending is prioritised and allows a focus on delivery and outcomes. Under Defence Reform, CDN will act as the clear point of accountability for the ringfence, working closely with industry and the MSHQ finance teams to ensure effective management.^[9]

On the four new budget holders, one for each of the quad, the statement added:

Funding and spend will be categorised into ‘invest, readiness and operate’—with the national armaments director holding the invest budget and MSHQ responsible for the operate budget and the readiness budget of the frontline commands. Balance of investment decisions will be made across the whole department, set against ministers’ strategic priorities to ensure resources match ambitions. The principal accounting officer will delegate multi-year budgets, in line with the Treasury’s departmental spending settlement, to each area. Financial year 2025–26 will be a transitional year, with quarterly reform programme milestones through the year and the bulk of the transformation complete by financial year 2026–27. The drive to reform defence will continue throughout this parliament.^[10]

The government has stated that defence reform is a parliament-long programme, and (as restated in the SDR) more improvements will come over the next 12 months—focused on increasing integration, reducing duplication, and improving delivery.^[11]

The government has also announced the creation of a new defence innovation body to “deliver cutting-edge military tech to British troops and create highly skilled jobs across the UK”.^[12] Further information on this was provided in the SDR.

1.3 UK spending on defence

The government also made pledges on defence spending ahead of the publication of the SDR. On 25 February 2025, Prime Minister Sir Keir Starmer announced plans to increase defence spending to 2.5% of GDP from 2027, and for the remainder of the current parliament.^[13]

In the 2023/24 financial year, the UK spent £53.9bn on defence.^[14] Spending plans set out in the 2024 autumn budget showed that defence spending was expected to total £56.9bn in 2024/25, increasing to £59.8bn in 2025/26. This is equivalent to an annual average real-terms growth rate of 2.4% between 2023/24 and 2025/26.

In the spring statement 2025, the government announced a £2.2bn uplift to the MOD budget for 2025/26, as per the intention to increase NATO-qualifying defence spending to 2.5% of GDP by 2027.^[15] The government said its ambition is for defence spending to reach 3% of GDP “in the next parliament when economic and fiscal conditions allow”.^[16]

However, since the publication of the SDR there has been further discussion of defence spending as part of the recent NATO summit on 24 to 25 June 2025. This included a new commitment from UK ministers (and other NATO nations) to raise spending to 5% of GDP by 2035 (using a new methodology combining ‘core’ defence spending and other related spending). This is discussed in section 4.1 of this briefing.

2. Conclusions and recommendations from the SDR

The government contends that the SDR signifies a “landmark shift” in the UK’s deterrence and defence, moving to “warfighting readiness to deter threats and strengthen security in the Euro-Atlantic in recognition of a rapidly evolving threat landscape”.^[17] The SDR outlines a vision for defence, the armed forces and wider society, and provides 62 recommendations, all of which the government has said it welcomes and will implement.

2.1 Key findings from the SDR

Described as “the plan for change for defence”, the SDR speaks in depth to how, for the first time since the end of the cold war, the UK arguably faced “multiple, direct threats” to its security, prosperity, and democratic values in a world “beset by volatility and deep uncertainty”.^[18] The reviewers contended this is a “generational challenge” which requires a “generational response”. The SDR argued that the UK had to prepare for scenarios that would have been previously considered unthinkable:

[…] the UK, with its allies—especially those in NATO—must once again be ready to deal with the most demanding of circumstances: deterring and preventing a full-scale war by being ready to fight and win. Until recently, such a war against another country with advanced military forces was unthinkable. It would likely be high-intensity, protracted, and costly in every way. Moving to warfighting readiness in this new era is essential.^[19]

The SDR argued that with rapid advances in technology “driving the greatest change in how war is fought for more than a century”, the UK must pivot to a new way of war.^[20] In addition, it said that the UK’s armed forces must “once again be able to endure in long campaigns” and that a renewed emphasis on home defence and resilience was also imperative.

The core vision of the SDR was that by 2035 UK defence would be a “leading tech-enabled defence power, with an integrated force that deters, fights, and wins through constant innovation at wartime pace”.^[21]

In support of this vision, the SDR made several overarching recommendations. Noting the starting point for the review was the government’s ‘NATO first’ policy, the SDR said that the UK needed to “step up” its contribution to Euro-Atlantic security.^[22] It said that “‘NATO first’ does not mean ‘NATO only’”, and that the UK needed to bolster its international partnerships and work with powers outside of the region. However, the SDR said that the fundamental importance of meeting NATO commitments and shaping deterrence in the Euro-Atlantic every day was “reflected in the enduring and mutually reinforcing roles that defence must fulfil”.

The three core defence roles identified by the SDR were:

• Role 1: Defend, protect, and enhance the resilience of the UK, its overseas territories, and crown dependencies.
• Role 2: Deter and defend in the Euro-Atlantic.
• Role 3: Shape the global security environment.^[23]

The SDR added that defence also had two further ‘enabling’ roles, to:

• develop a thriving, resilient defence innovation and industrial base
• contribute to national cohesion and preparedness^[24]

As part of the need to transform UK defence and fulfil these roles, the SDR identified three “fundamental changes in approach” from how the armed forces were currently constituted and how they operated. These changes were as follows:^[25]

• Integrated by design: The armed forces must “complete the journey from ‘joint’ to ‘integrated’” and be designed and directed as one force under the authority of the chief of the defence staff, and delivered according to this design by the single services and strategic command.

The integrated force must be capable of operating in different configurations: as part of NATO component commands by design; in coalition; and as a sovereign force. To deliver a step-change in lethality, the integrated force must be underpinned by a common digital foundation and shared data. Delivery of this capability should be a top priority.

• Innovation-led: Defence must embrace its role in seeding innovation and growth, rapidly adopting new technology to keep the integrated force at the forefront of warfare.

In particular, defence should build relationships with the investors behind the innovators. External expertise should be systematically accessed through a new defence investors’ advisory group whose membership includes venture capital and private equity investors, while private finance should be encouraged under new funding models. Existing structures should also be reorganised under the national armaments director to create a defence research and evaluation organisation alongside the new UK Defence Innovation (UKDI) organisation.

• Industry-backed: Defence must create a new partnership with industry. Under the forthcoming ‘Defence industrial strategy’ and the leadership of the national armaments director, this involves “overhauling acquisition processes from top to bottom”.

The SDR made several recommendations linked to this process, including that the UK take a new modular, segmented approach to defence procurement and rapid commercial exploitation, with at least 10% of the MOD’s equipment procurement budget spent on novel technologies each year. The SDR also said that exports and international capability partnerships should be “mainstreamed into acquisition processes from the outset”.

More widely, the SDR said that by more purposefully using its market power and by prioritising UK-based business, defence should also strive to deliver for the UK economy “while delivering for the warfighter”. The SDR reviewers argued that defence had “significant untapped potential to be a new engine for growth at the heart of the UK’s economic strategy” and maintained that success would also see significant improvement in defence productivity, competitiveness, exports and value for money.

The SDR also said that the transformation of UK defence “must ultimately be delivered by its people”. To that end, it made several specific recommendations regarding armed forces personnel and the civilian workforce, including an overall increase in regular personnel when funding allows.^[26] It also made the following recommendations to maximise the effectiveness of the ‘whole force’:

• To fulfil the roles set out in this review, there is no scope for reducing the number of highly trained and equipped regulars across all three services, even as the forces move to a much greater emphasis on autonomy. Overall, we envisage an increase in the total number of regular personnel when funding allows. This includes a small uplift in army regulars as a priority.
• Increasing the number of active reserves by 20% when funding allows (most likely in the 2030s) and reinvigorating the relationship with the strategic reserves.
• Reshaping the civil service workforce with an emphasis on performance, productivity, and skills, reducing costs by at least 10% by 2030.
• Releasing military personnel in back-office functions to front-line roles and automating 20% of HR, finance, and commercial functions by July 2028. This should be a minimum first step.^[27]

The SDR also called for reforming training and education so that it is more adaptive to operational lessons and creates greater capacity and flexibility through developing a single virtual environment.^[28]

On home defence and resilience, the SDR said a renewed focus was vital to modern deterrence and ensuring continuity in national life in a crisis. The SDR said reconnecting defence with society should be a starting point, which could be achieved in part through “expanding cadet forces by 30% by 2030 (with an ambition to reach 250,000 in the longer term)”.^[29] The SDR also said further work was necessary to ensure the security and resilience of critical national infrastructure. In addition, it said a new defence readiness bill should provide the government with powers in reserve to mobilise industry and reserves should “crisis escalate into conflict”.

The SDR said that the UK must continue to dedicate its independent nuclear deterrent to NATO. On the integration of the armed forces, the SDR also said there needed to be a reversal of the “hollowing out” of foundational capabilities and a restoration of their readiness to fight.^[30] An “immediate priority” should be a shift towards greater use of autonomy and artificial intelligence (AI) within the UK’s conventional forces. It said this shift towards AI and autonomy should “exploit the parallel development of a common digital foundation, a protected defence AI investment fund, and an initial operating capability for a new defence uncrewed systems centre established by February 2026”.^[31]

The SDR also said the armed forces should accelerate their transition to a ‘high-low’ mix of equipment; for example, through the Royal Navy’s ‘Atlantic bastion’ concept for securing the North Atlantic for the UK and NATO and its plans for hybrid carrier airwings.^[32] The SDR also said that with an integrated force fighting as one across all five domains, greater attention must be given to the space and cyber and electromagnetic (CyberEM) domains.^[33]

The SDR noted that under the ongoing defence reform programme strategic command would be responsible for delivering—at the direction of the new military strategic headquarters—many of the joint enablers and specialist capabilities for the proposed integrated force. It said the UK special forces represented a working model of the integrated force, leading the way in innovation of new technologies and systems across all domains. The SDR made further recommendations to strengthen the ‘foundational capabilities’ of the armed forces, by empowering defence intelligence; rebuilding defence medical services; targeted investment in joint support enablers and munitions; and restoring the strategic base from which the armed forces deploy.^[34]

On the timescale of reform, the SDR said that “prudent sequencing” was needed to ensure the armed forces “have what they need, when they need it”. However, it said fundamental reform should not be delayed:

There is no reason to delay in changing fundamentally how defence works […] leveraging defence reform—the ongoing programme of organisational and cultural change—as a driver for reform across the department of state and the armed forces. Unlike other departments in government, the MOD does not control the timetable for confrontation and conflict. ‘Events’ and the UK’s adversaries do. Bold and decisive action is needed. ‘Business as usual’ is not an option.^[35]

2.2 Commitments made by the government in response to the SDR

In his foreword to the SDR, Defence Secretary John Healey set out the following government ambitions in response to the SDR’s findings, outlining several key announcements under each one:^[36]

“‘NATO first’—stepping up on European security by leading in NATO, with strengthened nuclear, new tech, and updated conventional capabilities”.

Key announcements under this theme included:

• First European hybrid airwings. The government pledged to transform the UK’s aircraft carriers and combine fast jets, long-range weapons, and drones.
• First European laser directed energy weapon in service. The government pledged nearly £1bn of new funding to this aim.
• Greater European deterrence. The government pledged to build up to 7,000 new long-range weapons in the UK to provide greater European deterrence and to support around 800 jobs.

“Move to warfighting readiness—establishing a more lethal ‘integrated force’ equipped for the future and strengthened homeland defence”.

Key announcements under this theme included:

• ‘New hybrid navy’. The government pledged to deliver this capability through dreadnought and SSN-AUKUS submarines, “cutting-edge warships and support ships”, transformed aircraft carriers, and new autonomous vessels “to patrol the North Atlantic and beyond”.
• A “10 times more lethal” British army. The government said this would be achieved through armoured capability, AI, software, long-range weapons, and land drone swarms. It said it aimed to increase full-time troops to at least 76,000 into the next parliament.
• Next-generation Royal Air Force (RAF). The government pledged to create a next-generation RAF with F-35s, upgraded Typhoons, next-generation fast jets through the ‘Global combat air programme’, and autonomous fighters to “defend Britain’s skies and strike anywhere in the world”.
• Sovereign warhead programme. Ministers pledged to secure the UK’s nuclear deterrent with £15bn this parliament, “supporting 9,000+ jobs”.
• Homeland air and missile defence. The government pledged to protect the UK homeland with up to £1bn new funding invested in homeland air and missile defence.

• New CyberEM The government pledged to defend Britain from daily attacks in the grey zone (the space in between peace and war in which state and non-state actors engage in competition).

“Engine for growth—driving jobs and prosperity through a new partnership with industry, radical procurement reforms, and backing UK businesses”.

Key announcements under this theme included:

• Munitions. The government pledged to invest £6bn in munitions during this parliament—including £1.5bn in an ‘always on’ pipeline and at least six new munitions and energetics factories in the UK. It hoped this would generate over 1,000 jobs and boost export potential.
• Continuous submarine production. The government committed to up to 12 conventionally armed, nuclear-powered attack submarines through the AUKUS programme. The government has said that it will commit to continuous submarine production through investments in Barrow and Raynesway that will “allow us to produce a submarine every 18 months”.
• UK Defence Innovation. The government will establish UK Defence Innovation with £400mn to fund and grow UK-based companies.
• New Defence Exports Office: The government will create a new Defence Exports Office in the MOD to “drive exports to our allies and growth at home”.

“UK innovation driven by lessons from Ukraine—harnessing drones, data, and digital warfare to make our armed forces stronger and safer”.

Key announcements under this theme included:

• Innovation in autonomy. The government pledged to double investment in autonomous systems this parliament to boost UK export potential.
• New digital targeting web in 2027. The government will invest up to £1bn for the digital integration of the UK’s armed forces.
• New ‘drone centre’. The government committed to a new drone centre and accelerating the use of autonomous systems across the UK’s armed forces.

“Whole-of-society approach—widening participation in national resilience and renewing the nation’s contract with those who serve”.

Key announcements under this theme included:

• Renewal of military accommodation. The government pledged to invest at least £7bn this parliament in military accommodation, with over £1.5bn of new investment to fix forces’ family housing.
• More opportunities for young people. Ministers pledged to deliver a 30% increase in cadets by 2030 and to introduce a voluntary ‘gap year’ scheme./li>
• Whole-of-society approach. The government committed to a new UK strategic reserve by 2030 and the navy taking a leading role in protecting undersea infrastructure./li>
• New defence readiness bill. The government said it would legislate to improve national preparedness.

The SDR also reiterated much of the commitments from the defence reform programme, including the new military strategic headquarters, new national armaments director to drive the ‘Defence industrial strategy’, and new powers for the chief of the defence staff.

Similarly, the government again highlighted its commitment to raise defence spending to 2.5% of GDP by 2027, and its ambition to raise it to 3% in the next parliament. It said a new £11bn ‘Invest’ annual budget had been established under the national armaments director. The SDR said this would “fund kit for our front-line forces which is affordable and grows our UK industrial base”. In addition, it argued that a new partnership with industry and a decade of consistently rising defence spending would encourage more private finance to grow the UK’s “world-leading” scale-up and dual-use tech companies.

The government provided further details on its drive towards autonomous systems to shape UK military future and boost export potential in a release published alongside the SDR.^[37] Noting that the SDR said a shift towards greater use of autonomy should be an “immediate priority” for force transformation, the government pledged £4bn for autonomous systems (plus the investment of nearly £1bn for directed energy weapons this parliament as highlighted above) to boost “frontline capabilities while creating 300 skilled jobs across the country”. The government stated that more than £2bn of this new funding will come from the uplift in defence spending to 2.5% of GDP from 2027, and contended that it would enable autonomous systems, including drones, to improve the accuracy and lethality of the armed forces.

In addition, the government has since provided more detail on plans to increase armed forces lethality by improving their ability to rapidly find and strike enemy targets.^[38] It said the prioritisation of the ‘Digital targeting web’ will increase the pace and scale of change already being tested through army initiatives like ASGARD, which is being delivered to British troops deployed with the NATO Forward Land Forces (FLF) in Estonia.^[39] To this end, the government has launched procurement for a new open framework to encourage defence companies to submit concepts for new digital systems that could be integrated into ASGARD. The aim is to exploit advanced technologies such as AI and uncrewed capabilities, enabling the development of “advanced digital ‘decision’ making on the battlefield”.

As part of the government’s commitment to NATO, the defence secretary has also said that UK military liaison officers will join the development of FLF Finland for the first time.^[40] These officers will work with both Sweden, as the ‘framework nation’, and Finland as they develop FLF Finland—a “vital component” to strengthening NATO’s deterrence posture on its eastern flank.

3. Reaction to the SDR

3.1 Debate in the House of Commons

Defence Secretary John Healey made a statement to the House of Commons on the launch of the SDR report on 2 June 2025.^[41] Echoing many of the themes from the SDR, Mr Healey said the “world had changed and we must respond”, adding:

The SDR is our plan for change for defence: a plan to meet the threats that we face, a plan to step up on European security and to lead in NATO, a plan that learns the lessons from Ukraine, a plan to seize the defence dividend resulting from our record increase in defence investment and boost jobs and growth throughout the United Kingdom, and a plan to put the men and women of our armed forces at the heart of our defence plans, with better pay, better kit and better housing. Through the SDR, we will make our armed forces stronger and the British people safer.^[42]

Responding for the opposition, the shadow defence secretary, James Cartlidge, contended that the government had not articulated how all the commitments in the SDR would be funded, and without that it was an “empty wish list”.^[43] Mr Cartlidge called for the government’s forthcoming defence investment plan, which the government said in the SDR is due to be completed in autumn 2025, to detail exactly how the UK would fund these commitments.

Speaking for the Liberal Democrats, Helen Maguire agreed that the UK had entered an era of international instability, geopolitical conflict and global uncertainty, and faced a “once-in-a-generation risk”.^[44] Arguing that meeting generational risks will require making generational commitments, she welcomed the government’s readiness to accept all the recommendations outlined in the SDR. However, she also questioned how it would be funded. Helen Maguire welcomed the announcement of new funding for military housing and urgent repairs, yet she contended that “fixing our recruitment crisis and doing right by our service personnel requires more than sticking plasters”.

The chair of the House of Commons Treasury Committee, Dame Meg Hillier (Labour/Co-op MP for Hackney South and Shoreditch) said she strongly welcomed the SDR.^[45] However, she said that it had to be embedded in the long term, not subject to “chopping and changing and stopping and starting programmes [which] can cause real problems for our men and women on the ground”.

In response to the questions on funding, the secretary of state said:

The SDR is a vision for the next 10 years and beyond. It can be delivered within the spending commitments that this government have made. As the prime minister underlined this morning, those spending commitments were baked into the terms of reference, and have been confirmed by the reviewers. As he has said, we will spend what we need to deliver this review, and I am totally confident that we will meet the ambition of 3% in the next parliament.^[46]

3.2 External commentary

Many analysts welcomed the ambitions set out in the SDR but questioned how easy it would be to turn them into reality. For example, Matthew Savill, director of military sciences at RUSI, agreed with many of the SDR’s propositions, including the need to focus on innovation and different ways of waging war that meet the continually evolving threat landscape.^[47] He argued that this showed an important recognition that the UK armed forces were falling behind others in terms of capability:

A completely different approach to innovation and the relationship with industry will be needed to make rapid development function, with a recognition NATO should be setting more of the requirements for the UK, combined with a far more directed approach to building the armed forces. If previous language on integration was vapid and linguistically tortured fluff, then this SDR is blunter about the creation of a single force, designed from the top down. Indeed, reading the arguments made by the senior review team it is clear they regard root-and-branch reform of almost every aspect of defence as necessary to put the armed forces on the road to being ‘ready for war’. The SDR, probably not wishing to be alarmist, understates this concern, but the implication is clear: assuming this is what it takes to be ready for modern war, then the UK is lagging badly.^[48]

However, Mr Savill argued that the “difficult part” was delivering change, and the SDR was “light in many areas on detail about how these ideas will be implemented”. He highlighted the challenge of reforming defence procurement, for example, which has already been the subject of significant attempts at reform.^[49] Mr Savill also pointed to the challenges of cultural inertia and funding when considering whether the SDR would lead to true change:

If defence genuinely reforms and implements the SDR’s ideas rapidly and with enthusiasm backed by resources, this could be a turning point in the UK’s military capabilities. But if the usual inertia and budgetary churn prevail, the review may be remembered more for what it failed to force through than for what it achieved.^[50]

Olivia O’Sullivan and Dr Marion Messmer from Chatham House also questioned whether the SDR’s findings and recommendations could be fully implemented.^[51] They said the review was rightly “threaded through” with lessons from the conflict in Ukraine, including on the use of technology in warfare; the industrial production needed to sustain a fight against a peer adversary; and the whole-of-society effort required to fend off unconventional warfare, including cyberattacks and attacks on infrastructure. However, the authors also raised the question of funding when attempting to redesign UK defence capabilities to meet these challenges:

Having the review led by external experts has its benefits. But the UK Ministry of Defence (MOD) and armed forces must ‘own’ the implementation and make some difficult investment choices. This is especially true as the UK government has set an ambition to spend 3 percent of GDP on defence only at some point in the next parliament. Meeting all the SDR’s commitments in that budget will be tight.^[52]

They also suggested the SDR did not deliver what “many people had hoped for” on international coordination, namely any “hints that UK defence may be planning for a future in which it is less reliant on US partnership”.^[53] They believed the SDR acknowledged the United States’ security priorities had changed, and the resulting need for the UK to spend more and focus on European and homeland security, but said it “does little to address recent challenges created by President Donald Trump’s transactional and unpredictable approach to NATO”.

Despite this, Ms O’Sullivan and Dr Messmer hailed several measures the government was committed to taking forward, such as the national armaments director, ringfenced commitments for new technologies and approaching procurement with a focus on export potential and international collaboration. However, although they welcomed initiatives like the use of common digital systems, for example, they queried how these would sit with existing legacy systems:

The review also emphasises the use of common digital systems to drive truly integrated working and more effective armed forces. This would enable UK armed forces to better collaborate, and prevent service branches developing poorly integrated parallel digital architectures. This is a massive undertaking and a big step away from previous practice. Some legacy projects will continue siloed development unless there is the willingness to pull the plug or integrate them. For example, the SDR recommends a defence-wide secret cloud—how will this work with the Royal Navy’s Project Stormcloud? Could Project Stormcloud become the ‘secret cloud’ or are the requirements of the two projects incompatible? These are the kinds of tricky questions that will need to be worked out in the implementation phase.^[54]

Jointly authored analysis by Douglas Barrie et al for the International Institute for Strategic Studies (IISS) again drew the distinction between ambition and implementation. Drawing upon the IISS’ own analysis that Russia might be in a position to pose a direct threat to NATO nations in 2027, particularly the Baltic nations, should a ceasefire in Ukraine be agreed, the authors contended that the timelines for that implementation could prove crucial.^[55] They also argued, as the SDR itself recognised, that the review would need more than buy in from the armed forces and MOD:

Beyond funding issues, radical changes to procurement, defence innovation and industry practices are required, as are societal changes, including in education and training, in order to move towards ‘war-fighting readiness’.^[56]

Michael Martins from the British Foreign Policy Group also stressed the need to engage the rest of society on the SDR, and made similar points on the need for an ongoing financial commitment.^[57] He suggested the UK’s US partners would be paying close attention to these matters. He also argued that the government needed to develop a compelling case for the SDR to engage the public with:

Post-cold war UK politics has also not favoured sustained defence investment, where hard choices were between health and social welfare spending, rather than between defence and everything else. Without a compelling narrative—one that builds cross-party and public consensus, while also bringing business along—the SDR risks being viewed as a technocratic exercise, not a national priority—or worse, a fig leaf for another tax grab by HM Treasury at the autumn statement, further hurting the UK’s economic growth prospects. For the US, this matters. A fragile domestic consensus and a sputtering economy at home can make for a less reliable partner abroad.^[58]

Dr Anisa Heritage at the Royal Military Academy Sandhurst said that the SDR came close to the “stark reality” of preparing Britain for war.^[59] However, she contended that one side effect of the SDR was that the UK’s previous tilt towards the Indo-Pacific, exemplified in the Littoral Response Group, the Global Combat Air Programme (GCAP) and AUKUS programmes, had been “cut adrift”. She questioned whether this was the right defence posture for our time given the interconnectedness of the Euro-Atlantic and Indo-Pacific theatres.

Others, such as the Royal Academy of Engineering, questioned whether the UK had sufficient skilled technicians able to deliver the scale of the SDR’s ambitions.^[60]

4. Recent developments, including NATO summit in June 2025 and national security strategy

4.1 NATO summit, 24 to 25 June 2025

NATO heads of state and government and key partners met at the Hague in the Netherlands on 24 and 25 June 2025. At the summit, alliance members, including the UK, committed to raising defence spending as a percentage of GDP to 5% by 2035 (as defined by ‘core’ plus other defence-related spending as set out below). The Hague summit declaration stated:

United in the face of profound security threats and challenges, in particular the long- term threat posed by Russia to Euro-Atlantic security and the persistent threat of terrorism, Allies commit to invest 5% of GDP annually on core defence requirements as well as defence-and security-related spending by 2035 to ensure our individual and collective obligations, in accordance with article 3 of the Washington Treaty. Our investments will ensure we have the forces, capabilities, resources, infrastructure, warfighting readiness, and resilience needed to deter and defend in line with our three core tasks of deterrence and defence, crisis prevention and management, and cooperative security.^[61]

In a separate release ahead of the summit, the UK government indicated that existing spending on areas like energy security would now be included in NATO’s calculation:

The UK has long argued that investment in things like energy security and tackling smuggling gangs is vital to national security. That is reflected in the national security strategy and the spending review and is now expected to be recognised by NATO.

With the new 5% commitment on national security, the UK expects a projected split of 3.5% (core defence) and 1.5% (resilience and security) to be agreed at the NATO summit, with a target date of 2035.

Under NATO’s new estimate, the UK expects to reach at least 4.1% of GDP in 2027. All allies will review the trajectory and the balance of spend between defence and wider national resilience in 2029, when NATO next reviews its capability plans.^[62]

This approach was confirmed in the Hague declaration, which stated:

Allies agree that this 5% commitment will comprise two essential categories of defence investment. Allies will allocate at least 3.5% of GDP annually based on the agreed definition of NATO defence expenditure by 2035 to resource core defence requirements, and to meet the NATO capability targets. Allies agree to submit annual plans showing a credible, incremental path to reach this goal. And allies will account for up to 1.5% of GDP annually to inter alia protect our critical infrastructure, defend our networks, ensure our civil preparedness and resilience, unleash innovation, and strengthen our defence industrial base. The trajectory and balance of spending under this plan will be reviewed in 2029, in light of the strategic environment and updated capability targets. Allies reaffirm their enduring sovereign commitments to provide support to Ukraine, whose security contributes to ours, and, to this end, will include direct contributions towards Ukraine’s defence and its defence industry when calculating allies’ defence spending.^[63]

At the NATO summit, Prime Minister Sir Keir Starmer also announced plans for the UK to purchase 12 new F-35A fighter jets and join NATO’s dual capable aircraft nuclear mission.^[64] The government contends that this decision will support 20,000 jobs in the F-35 programme in the UK, with 15% of the global supply chain for the jets based in Britain, “supporting highly skilled jobs and opportunities for working people and delivering a defence dividend across the country”.

4.2 National security strategy 2025

On 24 June 2025, the government published its new national security strategy (NSS).^[65] The NSS is intended to bring together several strands pertinent to the UK’s security, including the SDR:

NSS 2025 brings together the various strands of work relating to national security that have been underway since the 2024 general election. This includes the SDR, strategic security review, AUKUS review, resilience strategy, China audit, the industrial and trade strategies and work on supply chains, intelligence assessment, development assistance, soft power, AI and technological advantage. While recognising the uncertainty of the present moment and the need for continued adaptation, NSS 2025 is designed to last the duration of this parliament.^[66]

The government also contends that the NSS takes on new significance following commitments made at the NATO summit:

This work takes on new significance because of our 2025 NATO summit pledge, a historic commitment to spend 5% of GDP on national security. This is a generational increase in defence and security spending, underlining the UK’s commitment to national security and honouring our commitment to be a leader in NATO. As the second largest economy in Europe and the third largest in NATO, this will have a considerable impact on the strength of our alliance. The UK has long argued that NATO needs to focus more on national resilience as well as conventional military threats. We have set the foundations for a new era for defence in the SDR. But unless we do more to increase our competitiveness and sovereign strengths—in crucial areas like science and frontier technology—we will lose our ability to generate wealth and risk falling behind our adversaries. National security today means so much more than it used to—from the health of our economy, to food prices, to supply chains, from safety on the streets to the online world. And as we move to 5%, we need a plan for how we will maximise this opportunity to make our nation stronger. That is the purpose of NSS 2025.^[67]

4.3 Other recent announcements

• On 12 June 2025, the government announced the launch of the recruitment campaign for the UK’s first ever armed forces commissioner (AFC), which it described as an “important step in this government’s commitment to renewing the nation’s contract with those who serve”. The AFC will be an “independent champion” for service personnel and their families, who the government states will have authority and discretion to investigate a wide variety of welfare issues that impact service life. This could include issues related to kit and equipment, unacceptable behaviours, or service accommodation.^[68]
• On 23 June 2025, the government announced that it had reached an agreement with Ukraine to share battlefield technology. It said this was aimed at boosting Ukraine’s drone production and linking up the UK’s defence industry with the “cutting-edge” technology being developed on the front lines in Ukraine.^[69]
• In a written statement on 1 July 2025, John Healey announced the establishment of the new UK Defence Innovation organisation and the renaming of the UK strategic command to become the “Cyber and Specialist Operations Command (CSOC)”, reflecting the command’s evolved role and enhanced responsibilities. The secretary of state described the announcements as “two major developments in our commitment to reform defence and the delivery of our strategic defence review”.^[70]

5. Read more

• Ministry of Defence, ‘The strategic defence review 2025: Making Britain safer—secure at home, strong abroad’, 2 June 2025
• House of Commons Library, ‘Strategic defence review 2025: NATO’, 18 June 2025; and ‘Strategic defence review 2025: The UK’s nuclear deterrent’, 3 June 2025
• NATO, ‘The Hague summit declaration’, 25 June 2025

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Cover image by Dominic King, UK MOD © Crown copyright 2014 on Flickr.