Executive summary
- Recent British strategic documents repeatedly emphasise a focus on ‘sovereignty’ but fail to define it. While definitions from sources other than His Majesty’s (HM) Government exist, these typically rely on simplistic three-tier models that cannot capture the nuanced trade-offs in defence procurement.
- To bridge this definitional gap, a more granular framework is needed. This would help HM Government to align its industrial strategies with realistic operational needs and send clearer signals to defence industry.
- This Primer proposes a new six-tier taxonomy when applying considerations of sovereignty to defence capabilities, ranging from absolute autarky to the pragmatic prioritisation of ‘off-the-shelf’ operational readiness.
Introduction
Sovereignty has been a prominent feature of recent British defence and national security strategies. The words ‘sovereign’ and ‘sovereignty’ are mentioned 35 times in the National Security Strategy, 25 times in the Strategic Defence Review, 24 times in the Defence Industrial Strategy, and 19 times in the Defence Investment Plan.[1] Yet, as pointed out in the Joint Committee on the National Security Strategy’s (JCNSS) 2026 report, none of these documents define what sovereignty means in the context of the United Kingdom’s (UK) defence capabilities.[2] In a sector marked by complex supply chains – from raw materials and research and development to components and sub-systems, workforce skills, and software ownership – pinning down what exactly sovereignty looks like is no simple task. Take the F-35 Lighting II Joint Combat Aircraft for example, one of the world’s few fifth-generation combat aircraft: this complex fighter has over 2,100 suppliers from around the globe.[3]
Given this definitional gap, and the heightened importance placed on the concept of sovereignty that recent official publications have placed, this Primer will explore existing definitions and taxonomies to identify where gaps remain. It then seeks to provide the starting point for a new taxonomy on the topic to help His Majesty’s (HM) Government in its efforts to develop a more granular – and usable – definition.
Existing taxonomy
Although its salience has clearly grown in recent years, the importance and challenge of defining sovereignty is not a new problem, nor is it unique to Britain. There are several recent examples that have attempted to define a basic taxonomy. The JCNSS drew together the knowledge of a number of witnesses; summarising sovereignty as ‘the ability of a country to “autonomously [sic] develop, sustain, and control critical technologies, capabilities, and supply chains vital to its military strength and strategic autonomy.”’[4] However, the inclusion of ‘strategic autonomy’ in the definition makes the statement somewhat circular. In a similar vein, HM Government’s publications have often referred to ‘operational independence’, a phrase which is often taken as a synonym for sovereignty.
In essence, ‘operational independence’ means the ability for HM Government to decide when and how to use a capability without any other country possessing the means to prevent it from doing so. The term is often used to describe Britain’s independent nuclear deterrent.[5] The Trident II D5 missiles are a United States (US)-designed and built missile that the UK ‘leases’ from a shared pool. Crucially, they carry a British nuclear warhead; thus, the UK can employ these weapons at a time and place of its choosing.
Assuming that sovereignty is a byword for operational independence may offer some clarity for the top-level definition, but this still leaves more questions than answers. As Box 1 shows, more detailed definitions have been provided by government and civil society, although these remain quite sparse in general. Most often, these attempts break sovereignty down into three types across a spectrum: essentially a ‘high-medium-low’ level of sovereignty. This has been done in the JCNSS’ report, in the Integrated Review of 2021, by some analytical reports produced by think tanks, and by some allied governments.
BOX 1: EXAMPLES OF THREE-TIER SOVEREIGNTY DEFINITIONS |
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| Joint Committee on the National Security Strategy The JCNSS’ report provided a diagram outlining ‘hypothetical levels of sovereignty’.[6] These were divided between full sovereignty at one end, with partial sovereignty below it, and no sovereignty at the other end. These were explained as: • ‘Full sovereignty’: ‘Proprietary technology, developed, owned, and built in the UK and operational use authorised by UK Government only.’ • ‘Partial sovereignty’: ‘Foreign-owned technology, built in the UK but with some components imported. Full understanding of the system, including ability to validate and verify system performance and security. Operational use authorised by UK Government only.’ • ‘No sovereignty’: ‘Foreign-owned technology, built and maintained abroad. No or only partial understanding of the system and lack of ability to validate and verify system performance and security. Operational use requires agreement of international partners.’ Integrated Review (2021) The Integrated Review formulated a short taxonomy for varying degrees of sovereignty, but it did so in application to the science and technology field rather than defence capabilities specifically.[7] However, the logic still applies to both – and there is a great deal of overlap with the role of science and technology in the defence sector. The Review’s approach was to introduce an ‘own-collaborate-access’ framework, intended to help inform different approaches to different emerging technologies, depending on the level of desired sovereignty or the areas where the British science and technology base was already ahead of competitors. These were defined as: • ‘Own’: Where the UK has leadership and ownership of new developments, although this will always involve elements of collaboration and access. Areas that HM Government wants to ‘own’ will be supported with better funding. • ‘Collaborate’: Where Britain can provide unique contributions that allow it to collaborate with others to achieve its goals. This can be supported by HM Government identifying strategic partners and creating the market and regulatory conditions for international collaboration. • ‘Access’: Where the UK will seek to acquire critical science and technology from elsewhere through options, deals, and relationships. This can be supported by schemes for investment in science and technology companies. Tony Blair Institute Similar to the Integrated Review, the Tony Blair Institute provided a brief taxonomy of sovereignty from a technological perspective in its paper ‘Sovereignty in the Age of AI: Strategic Choices, Structural Dependencies, and the Long Game Ahead’.[8] The paper explains that ‘A more realistic and grounded understanding of sovereignty that reflects the realities of interdependence…is therefore needed. Sovereignty…is not a binary condition to be achieved or lost. It is fundamentally a question of agency and choice’. It went on to identify a ‘persistent trilemma’ that requires balancing, arguing that no state can maximise all three simultaneously. This trilemma consists of: • Pursuing control by investing in domestic capability; • Accessing frontier capability through global systems; • Ensuring coherence across regulatory, industrial, fiscal, and diplomatic strategies. Government of Canada Canada shares a similar political and military heritage to Britain, and is among the many countries grappling with the need to define sovereignty in defence capabilities. The 2026 Canadian Defence Industrial Strategy introduced a ‘build-partner-buy’ framework.[9] In addition to this, the document explains that ‘Sovereign capabilities are those without which Canada cannot defend its sovereignty or meet its allied commitments’ and attempts to list those that fit such a category. However, the list in question has a wide-reaching scope: it is ten items long, and contains several subsets. The framework is explained as: • Build: In the areas of home-grown strength and key sovereign capabilities, new defence procurements will typically be directed to Canadian firms as a matter of policy. • Partner: Where Canada lacks the capability to build domestically or where there is advantage to working jointly with partners, partnerships will be defined by joint work, building, and the sharing of key Intellectual Property (IP) in a manner that reinforces Canadian sovereignty. • Buy: When it is not feasible to build domestically or partner, Canada will buy equipment from allies, with strong conditions that spur reinvestment into the Canadian defence industrial base and ensure sovereign control over operation and sustainment. |
Several themes emerge from these attempts at establishing a taxonomy. The first is that even with additional exploration, definitions are kept very top-level – so much so that almost all taxonomies avoid moving beyond a simple three-element framework. The sectors and precise definitions may change, but in essence, all of the examples settle on a high, middle, and low level of sovereignty. While there is utility in every example, their ability to be applied in a more precise manner across defence industrial strategy or procurement is still limited. A three-tier system cannot capture the nuanced trade-offs between the factors influencing defence industrial strategy, including hardware manufacturing, software modification rights, IP ownership, supply chain resilience, training, and sustainment. A more precise taxonomy is still needed to capture the complexity and global nature of modern supply chains.
A new taxonomy would build on these conceptual baselines by creating something more usable for defence industrial and procurement policies. This requires moving beyond three tiers towards a more detailed spectrum of categorisation that captures the wide array of trade-offs HM Government is faced with. Not only will this help the UK to consider where and to what extent it wants sovereignty across capabilities, but it will serve as a more useful demand signal to industry, particularly allied nations and allied industry seeking to work in or with the British defence market.
Towards a new taxonomy
A number of different approaches could be taken to develop a new taxonomy. For example, applying a definition of sovereignty to companies rather than capabilities could be one route. However, this would require mapping sovereignty against thousands of companies, as no single entity could provide a capability independently. Therefore a new taxonomy should focus on applying definitions to the capabilities themselves, rather than the companies that contribute to their development, delivery, and sustainment.
Expanding the number of ‘tiers’ in the different levels of sovereignty which HM Government might pursue in defence capabilities will help to provide a more useful framework to apply to defence industrial and procurement policy. However, this raises the problem of exactly how many tiers there should be – too many and a framework would become unwieldy. Setting an arbitrary number to apply definitions across the spectrum is also problematic: definitions will simply be flexed to fit the numbers. Therefore, the most logical approach is to start from the top and work backwards.
Tier 1: Absolute sovereignty (autarky)
At the most extreme end, sovereignty in defence capabilities would entail complete end-to-end control of the supply chain. This would include even the mining and processing of critical minerals needed to build and sustain the capability, as well as the specialised domestic workforce required across the supply chain. This level of sovereignty would also include all software and hardware used in the capability originating from firms both owned and located in the country. This would create absolute IP and design authority ownership: including total ‘digital sovereignty’, e.g., exclusive control over the source code and mission data. In sum, there would be no reliance on outside actors for any part of the production, use, or future development of a capability.
This is, however, an almost impossible level of sovereignty – and in most cases unnecessary to achieve. There would be few examples of this to point to today, although there would have been more in previous decades. Perhaps the most complex capability to fit this tier would be Chinese ballistic missiles such as the DF-26.[10] In particular, the critical mineral aspect of control is near impossible for the vast majority of individual countries to achieve, let alone also to maintain exclusive control over the rest of the supply chain. Even the People’s Republic of China (PRC), with its dominance of an array of critical minerals extraction and processing, would struggle to achieve total autarky.[11]
Tier 2: Effective sovereignty
A more realistic and achievable form of sovereignty exists beneath autarky, albeit one that would be reliant on third parties for the resources, and potentially a small number of select sub-systems or components. In this tier, the UK would have the potential for national control over the firms developing, building, and maintaining a capability. Similar to absolute sovereignty, this level would see Britain retain full design authority and IP ownership, ensuring that HM Government can unilaterally upgrade, maintain, and export the platform. One of the key differences between this tier and autarky would be the need to find reliable sources for the materials needed to allow the supply chain to function. Some examples that fit this description would be the DragonFire Directed Energy Weapon or the Supacat Jackal 3 vehicle.
Given the length of the list of materials needed to build modern defence equipment, this may necessitate a split even within this tier between secure and insecure supply chains. If the majority of the materials required are sourced domestically or with allied nations, such as aluminium from Canada or cobalt from Australia, then there is unlikely to be an interruption to supply. In extremis, however, it cannot be ruled out. Magnesium or tungsten imported from the PRC, for example – which accounts for 91% and 86% of global production respectively – is insecure. A halt to the flow of these imports is far more likely and would quickly result in either decreased or halted production.[12] In ‘peacetime’, Beijing has shown its willingness to weaponise its critical minerals chokepoints – in a period of direct confrontation, it would undoubtedly turn off the taps to its adversaries.[13]
Tier 3: Pooled sovereignty or ‘mutually assured disruption’
Pooled sovereignty is for capabilities which have been developed and produced in an agreed multi-nation framework and typically feature varying levels of co-development and co-production. As the cost and complexity of platforms has grown, so too has the requirement to work with partners to develop them. There are a number of examples of such programmes in recent years: the Eurofighter Typhoon; the Airbus A400M; the F-35 Lightning II Joint Combat Aircraft; the Global Combat Air Programme (GCAP); SSN-AUKUS; the Future Cruise/Anti-Ship Weapon (FC/ASW); the Meteor air-to-air missile; and many others. In many of these programmes, industrial input, control over exports and mission data, and sustainment is shared between countries. Not only do such arrangements share the economic benefits and spread development costs, they also help to build in ‘mutually assured disruption’. With several countries reliant on each other for sub-systems and components, the risk of causing disruptions is reduced as allies can reciprocate: it is not impossible to replace allied contributions to the shared supply chain, but it is time-consuming and brings additional cost.
There are several caveats to capabilities pursued through pooled sovereignty. Agreements can take precious time, often many years, to formulate and finalise. These agreements can result in divided workshare and political control, which can create inefficient production and the prospect of allies blocking potential exports, as faced by the UK over the potential sale of 48 Typhoons to Saudi Arabia in 2018.[14]
Of course, terms can be arranged in a way that attempts to minimise a partner’s ability to block exports, but there is always the risk that this leads to delays or even the collapse of programmes. Related to this is the degree to which the pooling of these programmes is relatively symmetric (where partners hold equal leverage) or asymmetric (where one dominant partner holds outsized control), with a balance of positive and negative trade-offs between both. For the most part, these trade-offs relate to higher levels of industrial efficiency when there is a clear lead partner versus a greater ability to influence a programme when the partnership is more evenly distributed.
Tier 4: Assured access
This tier encompasses foreign-developed capabilities over which HM Government maintains significant access, including the authority to modify, to develop spirally, or potentially even to re-export. Within this tier, there will be a variety of subsets depending on a mix of categories. At its fullest extent, this will include extensive co-production opportunities where HM Government onshores production, finds British subcontractors able to plug into (and help to expand) the supply chain, and where the UK is allowed both to develop and export spirally.
At the lower end of the spectrum, this might see HM Government supporting Britain-based firms capable of providing key subsystems or components to expand the global supply chain for select capabilities, as is the case in the Guided Multiple Launch Rocket System or Martin Baker ejector seats in multiple aircraft designs. Lacking overall design authority, this would see HM Government secure the necessary licences and mission data access to ensure operational relevance. At a minimum, assured access would mean that no foreign government could prevent the UK from maintaining or updating the capabilities it has acquired. All of this also necessitates a domestic engineering and maintenance workforce capable of performing these modifications and repairs.
One of the primary benefits of opting for an assured access model for select capabilities would be the ability to leverage the research and development work already done by allies. Co-production would allow Britain to invest directly into productive capacity and feed into global export demand. An example which would fit this category would be the UK’s approach to the Boxer armoured fighting vehicle.
Tier 5: Operational sovereignty
Operational sovereignty encompasses capabilities procured from allies and partners over which Britain holds limited maintenance, upgrade, or export authority, but retains full discretion over their deployment. However, because this would likely also mean a lack of access to IP, design authority, and the domestic skills base to repair these systems, as well as the supply chain to maintain them, operational sovereignty does operate under the prospect of closure. Were the providing nation to decide to withdraw support, operational sovereignty would last only as long as the stockpiles of spare parts.
Exporting nations are unlikely to change their minds on pre-agreed levels of support and ‘rules of engagement’ in this manner, as it would seriously damage their future exporting prospects – although the possibility nevertheless remains. Given this, it is probably necessary to add a caveat to HM Government’s definition of operational independence to recognise this (albeit unlikely) possibility. Examples which would fit this description would be Tomahawk Land Attack Missiles or C-17 Globemaster heavy airlift aircraft.
Tier 6: Operational capacity priority
It is worth considering that the point of sovereignty in the specific case of defence capabilities comes down to how it supports the wider goals of HM Government’s defence policies. At the top level this is threefold: Firstly, to deter and if necessary defeat adversaries; secondly, to maximise the economic benefits of defence spending; and thirdly, to reinforce alliances and partnerships through collaboration. On the first objective, empty magazines and glaring capability gaps undermine deterrence and therefore at times need to be prioritised over sovereign control of a weapon; they simply leave the nation vulnerable to pressure or attack by adversaries.
This is where the final tier of sovereignty comes into the taxonomy: possession of weapons is in itself a form of sovereignty, even if direct British control over certain weapons and enablers barely exists. Capabilities fitting this category would include those where the UK would struggle to develop and/or integrate British-origin systems in a timely manner. They would also include those where HM Government is willing to accept potential control restrictions over terms of use.
This tier would include mostly ‘off-the-shelf’ purchases of the capabilities that the UK needs to fill gaps, and to do so quickly. There are a number of recent examples of procurements that fit this description, such as the 2018 decision to procure American Mark 54 torpedoes for the Royal Air Force’s (RAF) P-8 Poseidon fleet (while waiting for Stingray torpedo integration), or the purchase of submarine-launched cruise missiles in the form of Tomahawk missiles purchased in 1998, 2004, and 2014, or the Naval Strike Missile bought in 2022.[15] Looking ahead, a number of gaps can be seen where it could make sense to prioritise having capabilities to hand for their deterrent value over ‘sovereign control’. Here, examples might include land-based Ballistic Missile Defence (BMD), air-launched anti-radiation missiles, or hypersonic strike capabilities.
Conclusion
Sovereignty is a crucial consideration when acquiring defence capabilities, but it exists on a complex spectrum rather than as a simple binary (or even ternary) choice. Modern supply chains, the enablers to allow a capability to function fully, and the digital architecture that sits behind all of this, are near impossible for any one state to possess to an autarkic level. HM Government has placed renewed emphasis on sovereignty as a factor in its procurement priorities, but it has not provided a clear definition, let alone a detailed taxonomy, for either itself or for the defence industry with which it engages.
This is a gap that should be filled, and work is underway to do so. Whenever new capabilities are acquired, they can be mapped against the taxonomy so that industry can position itself and its supply chain against the level of control that HM Government desires.
The six-tier taxonomy provided in this Primer is by no means exhaustive: it requires refinement and potentially expansion. Rather, the framework is designed to provoke thought and provide a starting point for a formal taxonomy which HM Government can tailor to whatever level of granularity it deems most useful.
Notes
[1] ‘The Strategic Defence Review 2025 – Making Britain Safer: Secure at home, strong abroad’, Ministry of Defence, 02/06/2025, https://www.gov.uk/ (checked: 23/09/2026); ‘National Security Strategy 2025: Security for the British People in a Dangerous World’, Cabinet Office, 24/06/2025, https://www.gov.uk/ (checked: 23/09/2026); ‘Defence Industrial Strategy: Making Defence an Engine for Growth’, Ministry of Defence, 08/09/2025, https://www.gov.uk/ (checked: 23/09/2026); and ‘The Defence Investment Plan: Equipping our forces, defending our future’, Ministry of Defence, 30/06/2026, https://www.gov.uk/ (checked: 23/09/2026).
[2] ‘The National Security Strategy: Fourth Report of Session 2024-26’, Joint Committee on the National Security Strategy, 27/03/2026, https://publications.parliament.uk/ (checked: 23/09/2026).
[3] ‘F-35 Lightning II: Economic Impact’, Lockheed Martin, No date, https://www.f35.com/ (checked: 23/09/2026).
[4] ‘The National Security Strategy: Fourth Report of Session 2024-26’, Joint Committee on the National Security Strategy, 27/03/2026, https://publications.parliament.uk/ (checked: 23/09/2026).
[5] For example, see: George Allison, ‘British nukes are operationally independent’, UK Defence Journal, 09/03/2025, https://ukdefencejournal.org.uk/ (checked: 23/09/2026).
[6] ‘The National Security Strategy: Fourth Report of Session 2024-26’, Joint Committee on the National Security Strategy, 27/03/2026, https://publications.parliament.uk/ (checked: 23/09/2026).
[7] ‘The Integrated Review 2021’, Cabinet Office, 16/03/2021, https://www.gov.uk/ (checked: 23/09/2026).
[8] Hilda Barasa et al., ‘Sovereignty in the Age of AI: Strategic Choices, Structural Dependencies and the Long Game Ahead’, Tony Blair Institute, 19/01/2026, https://institute.global/ (checked: 23/09/2026).
[9] ‘Security, Sovereignty, and Prosperity: Canada’s Defence Industrial Strategy’, Government of Canada, 26/02/2026, https://www.canada.ca/ (checked: 23/09/2026).
[10] Peter Wood and Alex Stone, ‘China’s Ballistic Missile Industry’, China Aerospace Studies Institute, 11/05/2021, https://www.airuniversity.af.edu/ (checked: 23/09/2026).
[11] It is worth noting that a temporary level of autarky could be achieved in certain capabilities via an aggressive stockpiling regime.
[12] James Hackett et al., ‘Critical Raw Materials and European Defence’, International Institute for Strategic Studies, 25/03/2025, https://www.iiss.org/ (checked: 23/09/2026).
[13] Joris Teer, ‘Beijing’s critical raw material weapon – And how to dismantle it’, European Union Institute for Security Studies, 12/05/2026, https://www.iss.europa.eu/ (checked: 23/09/2026).
[14] Paul Iddon, ‘Germany Blocked A Eurofighter Sale To Saudi Arabia, Then Lifted It. Will Berlin Do The Same With Turkey?, Forbes, 26/03/2024, https://www.forbes.com/ (checked: 23/09/2026).
[15] George Allison, ‘Britain to purchase MK54 lightweight torpedo array kits destined for P-8 Poseidon’, UK Defence Journal, 03/01/2018, https://ukdefencejournal.org.uk/ (checked: 23/09/2026); and ‘What is the state of Royal Navy land-attack missile capability?’, Navy Lookout, 06/02/2024, https://www.navylookout.com/ (checked: 23/09/2026).
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