Armed forces: UK future capability and requirements

Approximate read time: 45 minutes

On 16 July 2026 the House of Lords is due to debate the following motion:

Lord Harlech (Conservative) to move that this House takes note of the future capability of the United Kingdom’s armed forces in light of the current international situation.

1. Key points

• The UK faces its most challenging security environment since the Cold War, with NATO identifying Russia as the most immediate threat and China as a significant long-term strategic challenge. NATO highlights an increasingly interconnected landscape of state conflict, cyber threats, political interference and regional instability requiring a fundamental rethink of defence policy.
• Russia’s invasion of Ukraine was an inflection point for European security, demonstrating the return of large-scale state-on-state warfare in Europe. The conflict has reinforced the importance of military readiness, industrial capacity, stockpiles, innovation and the ability to sustain prolonged operations.
• Alongside conventional military threats, assessments emphasise the growing importance of hybrid threats, including cyber-attacks, sabotage, disinformation campaigns and attacks on critical infrastructure. The UK government and NATO argue that resilience, homeland security and civil preparedness must now sit alongside traditional military capabilities.
• The 2025 strategic defence review (SDR) concluded that the assumptions underpinning post-Cold War defence planning are no longer sufficient. It calls for a transition to “warfighting readiness”, arguing that the UK must be prepared to deter and, if necessary, fight and win a high-intensity conflict.
• A central proposal of the SDR is the creation of a more lethal and technologically enabled “integrated force”. This would combine personnel, conventional platforms, autonomous systems, artificial intelligence, data and digital networks across all domains of warfare.
• The review identified weaknesses in force readiness, recruitment, retention, stockpiles and procurement, arguing that parts of the armed forces have been “hollowed out”. While recent personnel figures show some improvement, the longer-term trend remains one of declining trained force strength.
• Across the services, the ‘integrated force’ model places greater emphasis on autonomous systems, drones, artificial intelligence and digital integration. Under the vision of the SDR, the army, Royal Navy and RAF are all expected to operate a mix of crewed and uncrewed capabilities while remaining focused on NATO’s collective defence requirements.
• The government’s 2026 defence investment plan (DIP) is intended to implement the SDR’s vision through major investment in defence capabilities, including autonomous systems, cyber defence, munitions, missile defence and digital integration. The plan also seeks to strengthen domestic defence industries and increase the armed forces’ warfighting readiness.
• While there is broad support for the strategic direction of the SDR and DIP, commentators, parliamentarians and defence experts have questioned whether funding and implementation plans are sufficient. A recurring concern is whether the UK can deliver its ambitions quickly enough to meet growing threats and NATO commitments.

2. Current strategic environment

2.1 International security environment

Global context

The government’s ‘Strategic defence review 2025’ (SDR) argued that, for the first time since the Cold War, the UK faced “multiple, direct threats to its security, prosperity and democratic values”.^[1] It identified a combination of conventional military threats, strategic competition, ‘sub-threshold’ activities, increased access to space and cyberspace, and rapid technological innovation as requiring a “generational response” and a “fundamental change” in the UK’s approach to defence.^[2]

The SDR identified Russia as an immediate and pressing threat to the UK and its NATO partners, while also highlighting the longer-term challenges posed by China, Iran, North Korea and instability in the Middle East.^[3]

NATO assessments of the international strategic environment have reached similar conclusions. Its 2022 ‘Strategic concept’ stated that “strategic competition, pervasive instability and recurrent shocks define our broader security environment”.^[4] NATO identified current threats as arising both from state investment in conventional, nuclear, and missile capabilities—often undertaken with “little transparency or regard for international norms”—and from the use of hybrid tactics, employed both directly and through proxies. It identified Russia as the “most significant and direct threat” to security in the Euro-Atlantic area. However, it also highlighted China’s growing influence, persistent terrorist threats, cyber-attacks and instability in Africa and the Middle East as challenges that “directly affect our security and the security of our partners”.^[5]

Russia

Russia’s invasion of Ukraine has dominated European security policy and influenced defence planning across NATO states. The SDR stated it was “a strategic inflection point” that:

[…] irrefutably demonstrated the changing and dynamic nature of the threat, with state-on-state war returning to Europe, adversaries using nuclear rhetoric in an attempt to constrain decision-making, and the UK and its allies under daily attack beneath the threshold of war as part of intensifying international competition.^[6]

The SDR contended the war had demonstrated the importance of readiness, military mass, industrial capacity and innovation, ammunition stockpiles, and the power of emerging technology. The SDR argued the UK must be ready to fight and win in order to deter and prevent full-scale war.^[7] It stressed the need for the UK to contribute to NATO’s collective defence requirements.^[8]

In addition to Russia’s war against Ukraine, NATO’s 2025 annual report highlighted a broader pattern of hostile activity directed towards NATO members by Russia, including cyber-attacks, sabotage and disinformation campaigns.^[9] It said that in response to the “more dangerous world”, NATO has “developed the most comprehensive defence plans since the Cold War”. This has included taking “significant steps to boost industrial capacity” and to deploy “combat-ready forces on the eastern flank”. It also stated that through the 2025 ‘Rapid adoption action plan’, allies have aimed to integrate “novel and innovative technologies into their armed forces, and ensure they have digital tools and practices necessary to become an alliance enabled for multi-domain operations”.^[10]

Military and defence commentators have also highlighted lessons emerging from the conflict in Ukraine, particularly regarding industrial capacity, ammunition stockpiles, electronic warfare, and the growing importance of drones and autonomous systems. For example, analysis from the International Institute for Strategic Studies (IISS), the Royal United Service Institute (RUSI) and the Centre for Strategic and International Studies suggest that future conflicts are likely to require a combination of technological innovation, armed forces personnel strength, and a resilient defence industrial base capable of sustaining prolonged operations.^[11]

China

Alongside concerns regarding Russia, policy makers identify China’s increasing global influence and its continued military modernisation as a long-term challenge shaping the international security environment. The SDR described China as a “sophisticated and persistent challenge” that is:

[…] increasingly leveraging its economic, technological, and military capabilities, seeking to establish dominance in the Indo-Pacific, erode US influence, and put pressure on the rules-based international order.^[12]

NATO’s strategic concept identified similar concerns about China’s military modernisation, technological competition, hybrid and cyber activity, actions to control critical infrastructure and its efforts to expand political and economic influence.^[13] In a speech on how the Secret Intelligence Service (SIS) was keeping the UK safe in a “world more dangerous and contested now than it has been for decades”, the UK’s chief of the SIS, Blaise Metreweli, identified China as a key player in the “global transformation taking place”.^[14] He said it was key that UK intelligence services continue to inform the government’s understanding of China’s rise and the implications for UK national security.

Another challenge identified by NATO is China’s “deepening strategic partnership” with Russia and the growing cooperation between China, Russia, Iran and North Korea. NATO’s 2025 report identified China, Iran and North Korea as countries supporting Russia’ war effort in Ukraine.^[15]

Middle East

Developments in the Middle East remain a further source of instability. The IISS’ ‘Armed conflict survey 2025’ argued conflict in Gaza, continuing instability in Syria, Lebanon and Yemen, and heightened confrontation between Israel and Iran have contributed to a volatile regional security environment.^[16] NATO similarly identified the volatility in its “southern neighbourhood” as a concern.^[17].

More recently, the conflict between Iran and the US and Israel has caused further instability. In a joint statement with the leaders of France and Germany in February 2026, Prime Minister Sir Keir Starmer called for diplomacy.^[18] The leaders’ said that the Iranian regime should end its nuclear programme, curtail its ballistic missile programme, end the repression of Iranians, and stop its support for armed groups abroad. Sir Keir also said he did “not believe in regime change from the skies”.^[19] Further information on this conflict and the UK government’s response can be found in the House of Commons Library briefing ‘Israel/US-Iran conflict 2026: Background and UK response’ (26 April 2026). In addition, the House of Lords Library briefing ‘Israel/US-Iran conflict 2026: Reopening the Strait of Hormuz’ (8 June 2026) sets out the importance of the strait to the global economy and UK and international initiatives to reopen the trade route.

Interconnected threats

A recurring theme within assessments of the current international strategic environment is that the threats are “global and interconnected”.^[20]. For example, NATO has argued that security threats can no longer be viewed in isolation and points to growing links between strategic competition, regional conflicts, cyber threats, disinformation campaigns, economic security, protection of critical infrastructure and technological rivalry.^[21] As a result, NATO and the SDR state that the current security environment requires defence policy to have a greater emphasis on resilience, industrial capacity, civil preparedness and the protection of critical infrastructure, alongside traditional military capabilities.^[22]

US policy

The SDR also acknowledged that given the US’s change in focus within the international strategic security context, European allies would need to do more for their own defence:

Changes in the strategic context mean that UK defence must plan on the basis that NATO allies may be drawn into war with—or be subject to coercion by— another nuclear-armed state. With the US clear that the security of Europe is no longer its primary international focus, the UK and European allies must step up their efforts.^[23]

US President Donald Trump has made comments that have led some to question the US’s commitment to NATO’s principle of collective security.^[24] He has also argued that European NATO allies should increase their defence spending and assume greater responsibility for European security. For instance, at the 2025 NATO summit, he emphasised that all member states should “share the financial burden of European defence spending” and welcomed allies’ commitments to increase defence expenditure.^[25] More recently, at the NATO summit in Ankara, Turkey in July 2026 the US joined other allies in reaffirming an “ironclad commitment” to collective defence under article 5 of the North Atlantic Treaty. The summit declaration also welcomed the fact that “European allies and Canada, working with the United States, are assuming greater responsibility for the alliance’s defence”.^[26]

The SDR does not explicitly address a situation where the US would not support a collective response to one or more of its NATO allies. However, it does make several references to the US’s changing security priorities and the implications of this shift. For instance, it notes there were “major questions about the future of European security that inevitably follow the United States’ change in security priorities, as its focus turns to the Indo-Pacific and the protection of its homeland”.^[27] The review concluded:

Fundamentally, the UK’s longstanding assumptions about global power balances and structures are no longer certain.^[28]

2.2 Hybrid threats and homeland security

Alongside conventional military threats, both the UK and NATO emphasise the growing significance of sub-threshold attacks and hybrid threats. These include cyber-attacks, sabotage, disinformation campaigns, economic coercion and attacks on critical infrastructure. The SDR stated the UK was facing “daily” cyber-attacks and coercive activity conducted by state and non-state actors across multiple domains.^[29] NATO has identified the need to build “national and alliance-wide resilience against military and non-military threats”.^[30]

Cyber security has been a particular area of concern. The NATO secretary general’s 2025 annual report notes that hostile cyber activity increasingly targets governments, military networks, critical infrastructure and private sector organisations, with the objective of disrupting essential services or undermining social resilience.^[31]

The National Cyber Security Centre’s (NCSC) 2025 annual review reported the UK had “faced a record number of nationally significant incidents”.^[32] To combat this threat to UK cyber security, it argued:

What is needed to operate in this environment are strategies to respond, deter and counter that are informed, context-aware and flexible. Understanding threat today is not just about detection; it is about outcompeting adversaries in insight and agility. We must be able to make sense of a complex, broad technical landscape at pace, and link this to geopolitical context, not least in understanding the intent of actors and our global exposure to them.^[33]

It therefore contended there should be a “huge emphasis on collaboration”.^[34]

The SDR argued the UK is “in constant confrontation with adversaries in cyberspace”.^[35] It contended the cyber and electromagnetic (CyberEM) domain is “at the heart of modern warfare, the enabling domain that integrates all others”.^[36] It highlights that “data and digital systems are the fundamental underpinnings of all modern military capabilities”.^[37] The NCSC argued that in spaces like military and critical national infrastructure systems, “the effort attackers might use to undermine the security of these communications is significantly higher”.^[38] The SDR called for cyber defence to become an integral part of military planning.^[39]

Protection of critical national infrastructure (CNI) has also become more prominent in defence planning.^[40] Concerns include energy networks, telecommunications systems, transport infrastructure and undersea data cables. In announcing the UK government’s defence investment plan in June 2026, Sir Keir Starmer highlighted the threats to underwater infrastructure as an example of hostile activity directed at UK interests.^[41] NATO has likewise identified resilience and infrastructure protection as essential elements of collective defence. Its 2025 annual report argued that disruption to energy, communications or undersea infrastructure could have significant consequences for both civilian society and military operations.^[42]

These developments have increased emphasis on resilience and civil preparedness. The SDR argued that “in a decisive shift from the post-Cold War era, a renewed emphasis on home defence and resilience is also imperative”.^[43] It advocates a “whole of society” approach to security.^[44]. NATO regards resilience as both a national responsibility and an essential element of collective defence under article 3 of the North Atlantic Treaty. Further information about UK government policy on civil preparedness and on NATO obligations on national resilience can be found in the House of Lords Library briefing ‘UK civil preparedness for war: Government strategy’ (19 March 2026).

3. Strategic defence review vision for transforming UK defence policy: Overview

The SDR was commissioned by the government shortly after it came into office in July 2024. The review was conducted independently by Lord Robertson (former Labour defence secretary and NATO general secretary), Dr Fiona Hill and General Sir Richard Barrons.^[45]

The review was published in June 2025. It made 62 recommendations, all of which were endorsed by the government.

At the time of its publication, then Secretary of State for Defence John Healey described the SDR as a “landmark shift” in UK defence and deterrence.^[46] The review argued assumptions underpinning UK defence planning after the Cold War would not meet current and future security threats. It contended the UK and its NATO allies “must once again be ready to deal with the most demanding of circumstances”: to deter and prevent a full-scale war, the UK must be “ready to fight and win”.^[47] It suggested such a war would be “high-intensity, protracted, and costly in every way”. The review argued the armed forces must be able to endure long campaigns, underwritten by a “thriving industry”. It also placed an emphasis on home defence and resilience in a security environment characterised by persistent sub-threshold and hybrid threats. The review called for a transformative reform of the way UK defence is organised and delivered. It recommended:^[48]

• a move to warfighting readiness that would require technological innovation at a “wartime pace”, strengthened homeland defence and resilience, partnership with industry that is ready to scale and sustain innovation and production, and “radical root-and-branch reform” in defence procurement
• a new, more lethal “integrated force” model for the armed forces that uses AI and autonomy alongside more conventional warfighting capabilities, which takes a “NATO first” approach
• a “whole of society approach”, widening participation in national resilience and renewing the nation’s contract with those who serve

The review argued that with “rapid” technological advances, the UK needed to “pivot to a new way of war”.^[49]

Commentators were largely supportive of the strategic direction set out in the review. However, they expressed doubt over its implementation and whether there would be sufficient investment to being forward its proposals. For instance, Professor of International Security at King’s College London Andrew Dorman questioned how the 62 recommendations would be funded and argued the SDR had adopted the “standard defence-review tactic of assuming efficiency savings”.^[50] Authors of the IISS’s Military Balance blog agreed that “funding will be key to implementation”.^[51] Funding is discussed in section 5 of this briefing.

Further discussion of the SDR’s key proposals can be found in the following briefings:

• House of Lords Library, ‘Strategic defence review 2025’, 4 July 2025
• House of Commons Library, ‘Strategic defence review 2025: Key points and paper series’, 24 November 2025
• House of Commons Library, ‘Strategic defence review 2025: NATO’, 18 June 2025

4. Current capabilities of the armed forces and the strategic defence review’s proposals for reform

4.1 Integrated force model and capability reform

A central theme of the SDR is the development of an ‘integrated force’, in which personnel, platforms, autonomous systems, data and digital networks are connected across all domains to improve readiness, resilience and military effectiveness.^[52]

The SDR argued the armed forces remained shaped by the risks and demands of the post-Cold War era, “optimised for conflicts primarily fought against non-state actors on Europe’s periphery and beyond”.^[53] It asserted that “simple metrics such as the number of people and platforms deployed are outdated and inadequate”. It said that in modern warfare:

It is through dynamic networks of crewed, uncrewed, and autonomous assets and data flows that lethality and military effect are now created, with military systems making decisions at machine-speed and acting flexibly across domains.^[54]

The SDR asserted an “immediate priority for force transformation should be a shift towards greater use of autonomy and AI within the UK’s conventional forces”.^[55]

Previous defence reviews have put forward “a fixed force design to be delivered by a specified date”.^[56] Instead, the SDR advocated a model of “constant innovation of the integrated force at wartime pace, delivered through a new partnership with industry”. The review argued this would allow the force to “evolve as threats and technology do”.

The review also reflected wider concerns regarding the resilience of the UK’s armed forces. It identified challenges relating to force size, readiness, resilience, stockpiles, recruitment and retention, and procurement. Many of these issues have been highlighted previously, for instance by the House of Commons Defence Committee, the National Audit Office and the House of Commons Public Accounts Committee.^[57] The review argued that in order to establish an integrated force “fit for war in the 21st century” the key task is to “transform the armed forces, restore their readiness to fight, and reverse the ‘hollowing out’ of foundational capabilities without which they cannot endure in protracted, high-intensity conflict”.^[58]

The SDR argued Defence must create a new partnership with industry to “develop a thriving, resilient innovation and industrial base that can scale in support of the integrated force”.^[59] It proposed overhauling the existing procurement process and introducing a segmented approach consisting of:

• major modular platforms (contracting within two years)
• pace-setting spiral and modular upgrades (contracting within a year)
• rapid commercial exploitation (contracting within three months), with at least 10% of the [Ministry of Defence’s] MoD’s equipment procurement budget spent on novel technologies each year^[60]

The SDR also advocated defence exports and international cooperation on military equipment be considered from the start when buying or developing new capabilities.^[61] The review recommended giving the MoD responsibility for defence exports again.

On munitions, the review called for targeted investment.^[62] It recommended restored stockpiles of munitions, parts and fuel be “ultimately dispersed across the UK and potentially to storage facilities in Europe”. The review argued:

Defence should maintain an ‘always on’ munitions capability so that production can be scaled up at speed if needed. It should also lay the industrial foundations for an uplift in munitions stockpiles to meet the demand of high-tempo warfare, with economic benefits felt across all four nations of the UK.^[63]

4.2 Armed forces personnel strength and workforce

The SDR argued that to maximise the effectiveness of the “whole force” there would be no scope for reducing the number of trained regulars across the three services.^[64] The review envisaged an increase in the total number of regular personnel when funding allowed. This would include a “small uplift in the army regulars as a priority”. The review also called for a 20% increase in the number of active reserves when funding allowed.

Table 1 presents trends on the size of the armed forces between January 2023 and January 2026. Overall, the total strength of the armed forces has decreased during this period.

(Ministry of Defence, ‘Quarterly service personnel statistics: 1 January 2026’, updated 4 June 2026.)

Table 1 notes:

1. Strength is the number of service personnel.
2. UK regulars are full-time service personnel, including nursing services, excluding full-time reserve service personnel, Gurkhas, mobilised reservists, military provost guarding service, locally engaged personnel and non regular permanent service.
3. Volunteer reserves voluntarily accept an annual training commitment and are liable to be mobilised to deploy on operations. They can be utilised on a part-time or full-time basis to provide support to the UK regular forces.
4. Other personnel include the serving regular reserve, sponsored reserve, military provost guarding service, locally engaged personnel and elements of the full-time reserve service.

The total strength of the UK armed forces service personnel at 1 January 2026 was 182,050, an increase of 1,270 (0.7%) since 1 January 2025. Since 1 January 2025, the number of regular forces, Gurkhas and other personnel have all increased.

However, the full-time trained strength (Royal Navy/Royal Marines and Royal Air Force) and full-time trade trained strength (army) total decreased between 1 January 2025 and 1 January 2026 by 0.5% (600 personnel). The Royal Navy/Royal Marines has increased by 0.2%, whilst the army and Royal Air Force decreased by 0.7% and 0.5% respectively, as shown in table 2.

(Ministry of Defence, ‘Quarterly service personnel statistics: 1 January 2026’, updated 4 June 2026.)

Table 2 notes:

1. FTTS and FTTTS includes all UK regular personnel, Gurkhas, and the relevant elements of the full-time reserve service (FTRS).

While full-time trained/trade trained strength has increased since 1 October 2025, the long-term trend is still one of decline (other than an increase between 2019 and 2021).^[65]

Other key figures on the size of the armed forces include:

• 14,340 people joined the UK regular armed forces between 1 January 2025 and 31 December 2025, an increase of 1,500 (12%) compared with the previous 12-month period.
• 13,500 people left the UK regular armed forces between 1 January 2025 and 31 December 2025, a decrease of 1,320 (9%) compared with the previous 12-month period.
• The trained future reserves 2020 (FR20) strength stood at 29,060 as at 1 January 2026, a decrease of 200 (1%) since 1 January 2025.^[66]
• 4,060 people joined the future reserves 20 between 1 January 2025 and 31 December 2025, an increase of 380 (10%) compared with the previous 12-month period.
• 4,010 people left the future reserves 2020 between 1 January 2025 and 31 December 2025, a decrease of 270 (6%) compared with the previous 12-month period.^[67]

Further information on the size of the UK armed forces and analysis of historical trends can be found in the House of Commons Library briefing ‘Strategic defence review 2025: Armed forces personnel’ (2 June 2025).

The SDR argued there was an armed forces workforce crisis that had been caused by “poor recruitment and retention, shoddy accommodation, failing morale and cultural challenges”.^[68]

Following the SDR’s publication, then Defence Secretary John Healey said “reversing the decline will take time”.^[69] He explained the government’s target was to increase the army to at least 76,000 full-time soldiers in the next parliament.

4.3 Army capability and transformation

The SDR argued the British army was in transition from the force required for the post-Cold War era to a force “ready to play its part in NATO’s ‘deterrence by denial’, requiring greater lethality, mass, and endurance”.^[70] The review noted that much of the army’s capabilities had been donated to Ukraine. It argued that as the army rebuilds, investment must be paired with changes to how it is organised, operates, and is equipped.

The review suggested that future land warfare will combine traditional armoured capability with large-scale use of autonomous and uncrewed systems (aerial and land), sensors and digital networks.^[71] The SDR envisaged the army’s future capabilities to be a dynamic ‘high-low’ mix of equipment, in which autonomous and uncrewed platforms are paired with traditional armoured vehicles and attack helicopters.

The review seeks to deliver a 10 times more lethal British army by “harnessing precision firepower, surveillance technology, autonomy, digital connectivity, and data”.^[72]. It also discusses the army’s new ‘recce-strike’ model: the army’s ability to find (recce) and destroy (strike) enemy targets. The review says this new model should “underpin the transformation of the two divisions and corps headquarters committed to NATO’s strategic reserves corps”.

Authors of the IISS’s Military Balance blog argued in June 2025 that the army’s current capabilities “fell short” of what was proposed in the SDR.^[73] It contended that the ambition set out in the review would be difficult to achieve without a “significant increase in investment in land capabilities, beyond what the government has committed to”. Matthew Savill, writing for RUSI, suggested the review was “realistic about what steps can be taken here, working with the forces as they are”.^[74] However, he criticised some of the ambiguity in the review, questioning: “what, for example, does increasing the army’s ‘lethality’ by a factor of ten mean?”.

Further information about the SDR’s recommendations on the army can be found in the House of Commons Library briefing ‘Strategic defence review 2025: The British army’ (12 December 2025).

4.4 Royal Navy and Royal Marines capability

The review explains the Royal Navy’s purpose is, like the other armed forces, to defend the UK, to deter and defend in the Euro-Atlantic, and to shape the global security environment.^[75] Specific tasks include continuing to provide the UK’s strategic nuclear deterrent, contributing to NATO’s maritime plans and focusing on securing the North Atlantic to counter Russian submarines and protect critical undersea infrastructure.

The SDR envisaged a future “hybrid navy” consisting of a “dynamic mix of crewed, uncrewed, and increasingly autonomous surface and sub-surface vessels and aircraft”.^[76] The review argued the navy will also need to develop next‑generation capabilities such as attack submarines. The SDR said the navy should move towards becoming a “more powerful but cheaper and simpler fleet” by developing a ‘high-low’ mix of equipment and weapons that exploits autonomy and digital integration.^[77]

The SDR advocated an ‘always on’ supply line for shipbuilding. It argued this was essential to retain industry skills and reduce the delays in delivering new ships. It called for more flexible regulation “to support vital experimentation in areas such as autonomy”, including through the creation of regulatory ‘sandboxes’.^[78] These ‘sandboxes’ are designated areas at sea in which the navy and industry could test and deploy new technologies.

According to the review, the navy must also play a “new, leading and coordinating role” in securing the UK’s critical undersea infrastructure and maritime traffic. It said the navy must work with wider government and commercial partners to develop enhanced maritime surveillance.^[79]

The SDR said over time there will need to be changes in how the navy develops its workforce and training. It argued:

As complex systems become easier to operate with a smaller training burden, the Royal Navy should adjust its personnel balance to include greater numbers of reservists to generate efficiencies and release regulars for front-line operational roles. As it reconsiders its training estate needs, the navy should ensure there is ‘capacity by design’ so that it can continue to provide training to allies and partners without impacting national requirements.^[80]

Some commentators have questioned whether the navy can meet its various commitments, given its current capabilities. For instance, Nick Childs, senior fellow for naval forces and maritime security at IISS, has argued that while the proposal for a hybrid fleet is an ambitious response to changing threats and technology, uncertainty remains about the fleet’s eventual size, composition and capability.^[81] He suggests delivery will be challenging because the navy must simultaneously modernise, maintain readiness, overcome personnel and industrial-capacity constraints, and integrate large numbers of autonomous systems while the technology is still being developed. He also said questions remain about whether “new technology can be delivered at the scale and speed now envisaged”.

The House of Commons Defence Committee’s 2024 report, ‘Ready for war?’, set out evidence it had heard on navy capability pressures arising from a combination of limited fleet numbers, personnel numbers, maintenance demands and delays to replacement programmes. Witnesses, including Dr Rowan Allport of the Human Security Centre, pointed to challenges such as those associated with the transition from older platforms to new frigates and support ships.^[82]

Further discussion on naval capability gaps, including commentary and parliamentary scrutiny, can be found in the House of Commons Library briefing ‘UK defence in 2025: Warships and the surface fleet’ (27 November 2025).

On the Royal Marines commando force, the SDR said the amphibious advance force operations remained a critical focus.^[83] It advocated these operations increasingly focusing on supporting NATO requirements, including integrating into the UK-led strategic reserve corps when appropriate.

4.5 Royal Air Force capability

The SDR said the role of the Royal Air Force (RAF) was to defend and protect the UK, its oversea territories and crown dependencies; contribute to NATO plans to deter and defend in the Euro-Atlantic; and help shape the global security environment.^[84] The SDR’s vision for the RAF focused on evolving aircraft, building warfighting readiness and enhancing resilience.

The review argued the RAF “must stay at the leading edge of combat air’s evolution”, through the transition from exclusively crewed combat air platforms to a future combat air system (FCAS) with a mix of crewed, uncrewed, and increasingly autonomous platforms, integrated into the UK’s digital targeting web.^[85] It also called for more airborne early warning and control aircraft and ground-based radar to enable the UK to “maintain round-the-clock airborne surveillance in support of UK and NATO offensive and defensive operations”.^[86]

In terms of personnel, the SDR argued the RAF needed “a wide range of skills and talent for the technology-enabled warfighting of today and tomorrow”. The review recommended:

Its focus should be on retaining unique experience to build leaders and specialists, while its plans to increase its reserves by 50% could be enhanced to make better use of specialist skills. Outstanding training is needed for the RAF to remain effective but current arrangements for fast jet training are inadequate, meaning UK pilots are currently sent abroad to train.^[87]

Endorsing the review’s recommendations, John Healey said the government would 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”.^[88] The government also pledged to protect the UK homeland with up to £1bn of new funding in homeland and missile defence.

Further information about the SDR’s recommendations on the RAF can be found in the House of Commons Library briefing ‘Strategic defence review 2025: The RAF’ (29 June 2026).

5. Implementation of the strategic defence review: Defence investment plan 2026

5.1 Overview of the defence investment plan priorities

Following the publication of the SDR, the government said it would “develop a new defence investment plan” to deliver the review’s vision.^[89] The government initially intended to complete the plan in autumn 2025, but it was instead published on 30 June 2026. Launching the plan, Prime Minister Sir Keir Starmer argued:

This game-changing investment will strengthen our armed forces on land, at sea and in the air, ensuring our servicemen and women have the cutting-edge capabilities they need to deter evolving threats and keep the British people safe.^[90]

The prime minister said the government was increasing defence funding “by a further £15bn, setting a new record”.^[91] He said spending would be almost £80bn a year by 2029.

The ‘Defence investment plan’ (DIP) has a 10-year focus but set out defence spending plans for the next four years, from 2026/27 to 2029/30. The Ministry of Defence (MoD) has committed to provide an annual update to Parliament on the delivery of the DIP commitments.

The DIP contains decisions intended to implement the SDR’s vision of strengthening warfighting readiness and to ensure that autonomous and AI technologies, as well as uncrewed systems, receive “the investment they need in the coming years”.^[92] The government has said the DIP is a summary of “the major investment choices the government has made for UK Defence”.^[93] Its stresses it is not the entirety of UK Defence’s budget or capabilities.

The remainder of this section provides an overview of the spending commitments in the plan and some of its key investment priorities. A detailed examination of the key funding commitments and an overview of defence spending and how the DIP will be funded can be found in the House of Commons Library briefing ‘Defence investment plans: Key decisions’ (2 July 2026).

5.2 Defence spending commitments

The DIP sets out UK defence spending plans over the four years from 2026/27 to 2029/30. The government announced an extra £15bn for defence, in addition to the allocation in the 2025 spending review. This would bring total planned spending across this period to £298bn.^[94]

Setting out details of the plan in the House of Commons, Secretary of State for Defence Dan Jarvis said most of the extra £15bn is “extra day-to-day spending for training and improving availability of ships and aircraft to increase our war-fighting readiness”.^[95]

Mr Jarvis contended this would mean:

[…] defence spending will now increase—in real terms—by 27% between 2023/24 and 2029/30. That is a bigger increase across a parliament than any present member of this House has ever seen. It means the £74bn allocated to our armed forces next year is now £20bn more than the last year of the previous government. And it means—by the end of this decade—the proportion of GDP spent on defence will now be higher than at any time during the last 30 years.^[96]

The government has set out how it plans to fund £10.3bn of the additional £15bn announced in the DIP but the remaining £4.7bn is due to be confirmed in the 2026 budget.^[97]

While the plan sets out the government’s defence investment priorities for the next 10 years, it outlines specific funding for key programmes and capabilities that the government is investing in over the next four years. Explaining this approach, the DIP stated:

Unlike previous plans, between 2030 and 2035, we are leaving unallocated spending to allow us to respond to the evolving threat and seize new opportunities as technology advances.^[98]

5.3 Key investment commitments

The government set out the DIP commitments around three key areas:

• transforming our armed forces
• backing British
• stepping up UK leadership^[99]

The remainder of this section of the briefing outlines several key measures categorised under these three areas.^[100]

Transforming the armed forces

• Autonomy: Over £5bn of spending into autonomous systems, including building a hybrid navy with new autonomous vessels and uncrewed sub-surface vessels; an army “transformed” by AI, autonomous vehicles and drones; and the development of a next-generation RAF with autonomous fighter jets capable of operating from land bases or aircraft carriers.
• Land lethality: Over £20bn to increase the army’s lethality 10-fold through autonomous systems, long range missiles, AI and armoured vehicles, underpinned by a “new doctrine of fighting by recce-strikes at all levels”.
• Cyber and electromagnetic: £2.5bn to grow the new defence cyber electromagnetic force.
• Space: Investing in UK Space Command to increase awareness in space activities and protect critical national assets in orbit.
• Morale and recruitment: Three above-inflation pay rises and a “generational renewal” of military housing.

Backing British

• British industry and skills: Creating nearly 60,000 new jobs compared to 2023/24 levels and investing in British skills, with new defence technical excellence colleges and funding defence degrees.
• Aerospace sector: Over £1.1bn of new investment to upgrade and sustain the Typhoon force into the 2040s; buying additional F-35s; developing collaborative combat aircraft; and spending £8.6bn to “drive the RAF towards becoming Europe’s first 6th generation air force”.
• Ship building: £1.3bn for new autonomous surface vessels, autonomous sub-surface vessels and a future common combat vessel, and £7.2bn on a combined force of 13 Type 26 frigates with Norway, five Type 31 frigates and fleet solid support ships.
• UK nuclear deterrent: Over £20bn more in the ‘defence nuclear enterprise’ over the next four years than the previous four years, to modernise the UK’s nuclear deterrent. The UK will also join NATO’s dual capable aircraft nuclear mission.
• AI and quantum: £1.6bn in UK defence innovation over the next four years, including embedding and expanding AI and quantum across the armed forces such as the global combat air programme, collaborative combat aircraft, project ASGARD (digital targeting web) and the hybrid navy.
• Land industrial capacity: Re-established onshore manufacturing of heavy barrel ordnance, with a new factory at Telford and using UK steel from Sheffield Forgemasters. These are already delivering artillery to Ukraine and will provide the barrels for certain army artillery howitzers.

Stepping up UK leadership

• Replenishing munitions: £11.1bn on munitions and weapons to increase UK stockpiles and ensure the armed forces has the “right high-low mix of capabilities”. It commits to building at least six new energetics factories.
• Digital targeting web: £1.8bn investment to integrate the armed forces through a new digital targeting web. This will connect sensors, deciders and effectors across the integrated force. It will be “underpinned by world leading AI and software”.
• Critical underwater infrastructure: £330mn new investment into critical underwater infrastructure protection to further deter hostile activity in and around UK waters.
• Integrated air and missile defence: £790mn to enhance protection of the UK homeland and overseas bases from air, drone and missile threats over the next four years. This will include spending on new radars and sensors and building a new integrated air, space and missile defence operations centre.

5.4 NATO spending commitment

When the SDR was commissioned in July 2024, the reviewer’s remit was to produce an SDR that was “deliverable and affordable within the resources available to Defence within the trajectory to 2.5%”.^[101]

However, in February 2025 the prime minister committed to increasing defence spending to 2.5% of GDP by 2027 and to 3% in the next parliament, when fiscal and economic conditions allowed.^[102] The SDR reviewers refer to the February 2025 commitment in their foreword to the SDR:

What is also significant is the ambition to spend 3% of GDP on defence in the 2030s if economic and fiscal conditions allow. Given that the present 2.3% (which includes significant investment in the nuclear deterrent, the nation’s top defence priority, and other core commitments) might have forced savings in essential capabilities, this is good news.^[103]

Alongside NATO allies, at the 2025 Hague summit the UK committed to raise defence spending as a percentage of GDP to 5% by 2035, with 3.5% of GDP designated for core defence capabilities and 1.5% for broader national resilience and security measures.^[104] The UK government has said it remains committed to meeting its obligations.^[105]. It said all allies would review the trajectory and spend in 2029, when NATO next reviews its capacity plans.

Following the publication of the DIP, Chancellor of the Exchequer Rachel Reeves reaffirmed the government’s commitment to the NATO defence investment pledge:

From 2027/28 onwards, the UK will spend 2.7% of GDP on core NATO defence spending, solidifying its position as the NATO alliance’s third-largest cash spender, behind only the US and Germany. The government has committed to increasing defence spending to 3% of GDP in the next parliament, with funding and plans to be set out at the next spending review where defence must be the number one priority. Alongside NATO allies, the UK has committed to reach 3.5% of GDP on defence spending by 2035. The UK remains committed to meeting its obligations to the defence investment pledge. […] This is more money for UK defence, spent more effectively to ensure our service personnel have the capabilities they need to deter and fight now, whilst driving out waste and inefficiency.^[106]

The chancellor set out where some of this defence funding would be allocated:

This will support £5bn investment in drones and autonomous systems, the UK’s largest ever investment in drone warfare, and learning the lessons of Ukraine. It will fund strike and surveillance drones, a new hybrid navy as well as uncrewed land vehicles. It will also support the next generation of RAF aircraft, with £8.6bn investment under the global combat air programme with Italy and Japan, and £300m for the development of collaborative combat aircraft. It will also support an £11bn investment for munitions and weapons to increase UK stockpiles, at least six new energetics factories, and £3.2bn in space capabilities. And it will deliver the UK’s renewal of the nuclear deterrent, with £64bn of investment to build new submarines, develop a sovereign warhead and buy F35A jets.^[107]

5.5 Reaction to the DIP investment decisions

Comments before the DIP’s publication

On 11 June 2026, ahead of the publication of the DIP, John Healey, then defence secretary, and Al Carns, then minister for the armed forces, resigned from their ministerial positions. They cited the level of investment set out in the draft DIP as a reason for leaving their government posts.

Mr Healey argued the plan “falls well short of what is required for defence and the country at this dangerous time”.^[108] Mr Carns said the draft plan was “not built for the threat we face”. He argued it was “neither transformative enough nor sufficiently funded”.

In evidence to the House of Lords International Relations and Defence Committee on 16 June 2026, Chief of the Defence Staff Air Chief Marshal Sir Richard Knighton also cautioned about the consequences of insufficient defence spending. He told the committee:

The thing that I am most concerned about is the level of day-to-day activity funding, […] the resource departmental expenditure limit, because that funds operational activity and drives exercises and training.^[109]

He warned they would have to “dial back our activities and our exercise and operational activity if the level of resource funding that is available to us does not increase”.^[110]

Parliament’s reaction to the DIP

The DIP was published on 30 June 2026. The following day, during prime minister’s questions in the House of Commons, Leader of the Opposition Kemi Badenoch argued the “limited plan” had “completely unravelled” because “[the prime minister] has not found the money to pay for it. It is £5bn short”.^[111]

Speaking in response to the government’s statement on the plan in the House of Commons, Shadow Secretary for Defence James Cartlidge argued the plan had “virtually no more cash” than had been in the draft plan that had led to John Healey’s resignation and was also “too late”.^[112] He explained he took this view because “much of the capability that it contains will not be in service until the 2030s, when the threat we face is right now”.

Liberal Democrat Spokesperson for Defence James MacCleary agreed that the DIP was “too little, too late”.^[113] Mr MacCleary also argued there was a “significant gap between the ambition and the resources required”.

Both Mr Healey and Mr Carns welcomed the extra money that had been added since their resignations to the final version of the DIP. Mr Healey acknowledged that the DIP built on “the record increase in defence investment that we as a Labour government have made”.^[114] However, he argued further work needed to be done to meet the UK’s NATO spending commitments:

However, threats are still growing, demands on defence are still rising in this dangerous world and today’s step means that, as a nation, we will be spending 2.7% of GDP on defence in 2030, the date when NATO warns we could face a Russian attack. With European security at stake, does my right hon. Friend agree that more needs to be done in the months ahead, beyond the DIP, to develop a clear, credible funding plan that will hit 3% and meet our NATO commitment to 3.5% by 2035?^[115]

Chair of the House of Commons Defence Committee Tan Dhesi (Labour MP for Slough) has also called for more detail about how the UK will meet its 3% and 3.5% of GDP targets.^[116] Mr Dhesi argued the plan lacked a “clear timeline”, which in turn risked:

[…] leaving Parliament, and indeed industry, without a clear line of sight on future capability, timelines and funding. So the focus must now be on whether the ambition is matched by a credible delivery plan—and how exposed this leaves the UK and our forces in the short term to the growing threats we face.^[117]

While Mr Dhesi welcomed the “additional investment, particularly in readiness, nuclear capacity and support to Ukraine”, he stressed the UK needed to properly invest in defence.^[118] He highlighted the warnings from the prime minister that NATO needed to be ready for a Russian attack by 2030.

Reaction from the defence and security sectors

Commentary from defence and security experts and those in the sector have generally welcomed the government’s willingness to increase defence spending and prioritise emerging technologies. However, analysts have questioned whether the level of funding and pace of implementation will be sufficient to deliver the government’s ambitions.

General Sir Richard Barrons, co-author of the SDR, welcomed the fact the DIP contained a “decent transformative element”.^[119] However, he argued the funding package remained insufficient given the scale of the challenge facing UK defence. He said “it is still not going to crack” the issue of adequately funding the services. He also warned that the UK was “not keeping up with our allies, we’re certainly not keeping up with our enemies”, and argued that unless the UK committed additional resources to defence, “we are simply not going to be ready to defend this country properly”.

Matthew Savill, director of military sciences at RUSI, welcomed the increase in day-to-day spending, describing it as “necessary” to sustain training and operations.^[120] However, he argued the plan was heavily dependent on the successful adoption of new technologies. He described the DIP as “a bold bet on technological solutions with no margin for error if procurement is not speedy and implementation rapid”. He also noted that the overall financial settlement remained “relatively modest” when compared with the scale of investment needed to rebuild readiness and capability across the armed forces.

Writing on the Military Balance blog, IISS analysts also gave a mixed assessment. They suggested the government had produced a plan that would provide additional resources and make difficult choices about future capabilities.^[121] The authors argued that all three services appeared to have “won and lost battles” with “platforms sacrificed to make further financial headroom for yet-to-be-fielded, or in some cases developed, capabilities”. They concluded that the additional £15bn announced remained “well short of what some argued was needed”. The authors also highlighted concerns about the funding model underpinning the plan, noting that £4.7bn of the package had yet to be identified and describing this as “a worrying gap in finances yet to be resolved”.

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