What is Data Sovereignty and why is it important for defence

In the contemporary digital landscape, data has emerged as a fundamental asset of national power, comparable to traditional resources like oil or physical territory.

As nations and organisations migrate their critical infrastructures to the cloud, the concept of data sovereignty has shifted from a niche legal concern to a primary pillar of national security and strategic autonomy.

At its core, data sovereignty refers to the principle that digital information is subject to the laws and governance structures of the nation-state within which it is collected, processed, or stored (1). For the sectors of national defence and critical infrastructure resilience, the implications of this concept are profound. Achieving true sovereignty requires more than just local storage; it demands a comprehensive understanding of jurisdictional overreach, technical control, and the ability to maintain operational continuity in an increasingly fractured geopolitical environment.

The Foundation: Defining the Digital Borderline

To understand the importance of data sovereignty in a defence context, one must first distinguish it from related but distinct concepts such as data residency and data privacy. Data residency relates specifically to the geographic location where data is physically stored at rest (2).

While residency is a component of sovereignty, it is insufficient on its own. A nation may store its defence data within its physical borders, but if that data is managed by a foreign-owned corporation, it remains susceptible to the legislative reach of that corporation’s home country. A prime example is the United States' CLOUD Act, which can compel US-based providers to hand over data regardless of where the servers are physically located (7).

True data sovereignty ensures that the data is not only physically present but also legally protected from foreign intervention, ensuring that the originating state retains absolute authority over its entire lifecycle (2). Without this distinction, a nation is essentially "renting" its security from a third party that may, at any moment, be compelled by its own home government to provide access to those "rented" assets. In the realm of national security, this creates a vulnerability that no amount of physical border security can mitigate. Sovereignty acts as the digital equivalent of territorial integrity; it is the right of a state to exercise exclusive authority over its digital domain without external interference.

Capability Sovereignty: Beyond Data Residency

To help us understand we approached former British Military officer and founder of MissionOpsAI, James Milnes:

The data sovereignty literature has established a clear distinction between data residency and data sovereignty. This paper introduces a third term that is essential to the AI context: capability sovereignty.

Capability sovereignty refers to the ability of a nation-state or organisation to control the AI systems that process its data, make decisions on its behalf, and exercise autonomous agency within its operational environment. It is not sufficient to control where the data sits if the system reasoning over that data is foreign-controlled. Capability sovereignty demands control of the entire stack: storage, processing, inference, model governance, and the audit trail of autonomous decisions.

The distinction is not merely theoretical. A UK defence organisation may store classified intelligence in a UK-sovereign data centre, encrypted with UK-controlled keys, subject to UK data protection law. If that organisation then transmits a summarised extract to a US-hosted AI for analysis and planning support, the capability dependency has not been eliminated; it has been shifted one layer up the stack, to a layer that is harder to see and harder to govern.

The Dependency Ladder

Capability sovereignty can be understood as a ladder of dependencies, each of which must be assessed independently:

•            Hardware: are the chips and servers subject to US export controls or foreign maintenance contracts?

•            Operating system and virtualisation: are the foundational software layers operated by foreign-jurisdiction entities?

•            Model provenance: was the AI model trained on data subject to foreign intellectual property law, and does the model architecture embed US export-controlled technology?

•            API and integration layer: does the orchestration platform route queries through foreign-jurisdiction infrastructure?

•            Support and maintenance: do foreign nationals have administrative access to systems processing sensitive data?

The UK Ministry of Justice’s sovereign questions framework (3) provides a useful starting point for this analysis, but it was designed for data systems, not AI systems.

Defence: Maintaining Operational Freedom in the Digital Theatre

For defence organisations, the stakes of data sovereignty are existential. Modern warfare is increasingly data-centric, relying on real-time intelligence, autonomous systems, and interconnected command-and-control networks. In this environment, cyber defence sovereignty is far more than a regulatory requirement; it is a prerequisite for operational freedom (4). If a nation lacks sovereignty over its military data, it risks a scenario where a third-party provider or a foreign government could throttle access to critical information, censor communications, or even extract sensitive intelligence during a conflict.

This "strategic dependency" can undermine the very foundation of national security, as the ability to defend a nation becomes contingent on the goodwill and legal frameworks of foreign entities (4). When every sensor, drone, and soldier is a data point, losing control over that data is equivalent to losing control over the battlefield itself. Sovereignty ensures that the "kill chain" remains entirely under domestic jurisdiction, preventing adversaries or even "frenemies" from gaining a digital veto over military operations. This is particularly vital when considering the longevity of military programmes; a fighter jet may have a 40-year lifespan, during which the geopolitical alignment of a technology provider could shift significantly.

The 'Hyperscaler' Dilemma: Navigating Global Cloud Risks

The transition to cloud computing has complicated this pursuit of autonomy. Many defence departments are eager to leverage the scalability and innovation of public cloud providers, often referred to as "hyperscalers", yet they must grapple with the inherent risks of this dominance. As techUK notes, achieving digital sovereignty in the defence cloud requires a practical and nuanced approach that balances the benefits of commercial innovation with the necessity of sovereign control (6).

This involves creating "sovereign requirements" that mandate specific protections for classified workloads. This ensures that even if data resides on a global platform, the encryption keys and administrative access remain under the exclusive control of the host nation (6). The goal is to benefit from the speed of the commercial sector without falling into a trap where the nation’s strategic data is handled by staff or systems subject to foreign subpoena or surveillance. It is a delicate balancing act: how do you use the world’s best technology without giving the world’s most powerful corporations the keys to your national secrets?

Resilience: Mitigating Dependency and Vendor Lock-In

The concept of resilience is inextricably linked to how a state manages its data. Resilience refers to the ability to withstand, adapt to, and recover from disruptive events, whether they are cyberattacks, physical sabotage, or geopolitical shifts. Data sovereignty enhances resilience by reducing "vendor lock-in" and "state lock-in." When a government maintains sovereign control over its data, it ensures that it can migrate its digital assets between providers or revert to on-premise solutions without losing access to its intellectual property or operational history (5).

Without this control, a nation’s critical functions become brittle. Imagine a scenario where a diplomatic rift leads a foreign cloud provider to suspend services to a nation's energy grid or hospital systems. If the data is truly sovereign, the nation has the legal and technical means to move that data to a new environment or manage it locally. If not, the nation is effectively held hostage by its own digital infrastructure (5). Sovereignty provides the "exit strategy" that is essential for long-term national survival. It allows a state to maintain a "cold standby" of its essential services, ready to be repatriated at a moment’s notice should the global political climate turn hostile.

Strategic Autonomy: Lessons from Canada and the EU

The Government of Canada’s white paper on data sovereignty highlights that the legal reach of foreign governments is a primary risk factor in the public cloud (7). For instance, if a Canadian government agency uses a provider headquartered in a different jurisdiction, that provider may be legally compelled to provide access to Canadian data to foreign law enforcement or intelligence agencies without the Canadian government’s knowledge or consent (7). This risk of "extraterritoriality" means that even the most secure encryption can be bypassed if the legal mandate is strong enough in the provider's home country.

Cyber Threat Intelligence Analyst, Piers Kontic-Coveney highlights when assessing these risks:

"Extraterritorial entities don't need to breach your systems, they may only need to ask the right question of the right company under the right statute, and the intelligence picture built on that data becomes legally accessible to them, quietly, lawfully, and without notification."

This reality reinforces why it is not enough for data to reside domestically if the entity managing it is subject to foreign legislative reach. In Europe, this realisation has pushed digital sovereignty to the centre of economic and security policy. The European Commission has championed the idea of a "Data Union," aimed at creating a single market for data where European rules, particularly regarding privacy and security, are fully respected (8).

This initiative is designed to empower European businesses and public administrations to retain control over their data, thereby fostering a more resilient digital economy that is not entirely dependent on non-European technology stacks (8). The World Economic Forum further emphasises that Europe’s quest for digital sovereignty is driven by the need for "strategic autonomy" (9). In an era where technology is used as a tool of geopolitical competition, the ability to develop and control one’s own digital infrastructure is seen as a necessary condition for maintaining political independence (9).

Practical Governance: Asking the Right Sovereignty Questions

The practical implementation of data sovereignty often begins with rigorous risk assessment. The UK Ministry of Justice, for instance, provides a framework of "sovereign questions" that organisations must ask when handling sensitive information. These questions include: Who has access to the data? Where are the support staff located? Which country’s laws apply to the service provider? (3).

For defence agencies, these questions are the first line of defence against data leakage. If a support technician in a foreign country can access a database containing the coordinates of military assets or the personal details of service members, the sovereignty of that data has been compromised, regardless of where the server is located (3). Sovereignty, therefore, is as much about who can touch the data as it is about where the data lives. Building resilience requires a "zero trust" approach to foreign jurisdictions, ensuring that no external entity has the "keys to the kingdom." It demands that we scrutinise the entire supply chain, from the silicon in the chips to the developers writing the code, to ensure that no "backdoors" are built into the systems that protect our way of life.

Conclusion

Data sovereignty is the bedrock upon which modern defence and national resilience are built. It provides the legal and technical safeguards necessary to protect a nation's most sensitive information from foreign overreach and ensures that critical infrastructure can function independently during times of geopolitical instability. By understanding the nuances of jurisdictional control (1), addressing the risks of the public cloud (7), and pursuing strategic autonomy (9), nations can navigate the complexities of the digital era without sacrificing their security.

The digital "high ground" is no longer just a metaphor; it is a literal requirement for safety in the 21st century. As we look toward the future, the ability to assert "data authority" will likely be the defining factor in a nation's capacity to protect its citizens, maintain its place on the global stage, and ensure that its sovereign decisions are made in the halls of its own parliament rather than the boardrooms of a foreign tech giant.

---

Also By Us:

References

(1) IBM. (2024). What is data sovereignty? https://www.ibm.com/think/topics/data-sovereignty

(2) Imperva. (n.d.). Data sovereignty. https://www.imperva.com/learn/data-security/data-sovereignty/

(3) Ministry of Justice. (2023). Data sovereignty. https://security-guidance.service.justice.gov.uk/data-sovereignty/

(4) Stormshield. (2023). Cyber-defence: Sovereignty is far more than just a regulatory requirement.https://www.stormshield.com/news/cyber-defence-sovereignty-is-far-more-than-just-a-regulatory-requirement/

(5) Kahootz. (n.d.). Data sovereignty explained. https://www.kahootz.com/data-sovereignty-explained/

(6) techUK. (2023). Achieving digital sovereignty in defence cloud: A practical guide.https://www.techuk.org/resource/achieving-digital-sovereignty-in-defence-cloud-a-practical-guide.html

(7) Government of Canada. (2018). Government of Canada white paper on data sovereignty and public cloud.https://www.canada.ca/en/government/system/digital-government/digital-government-innovations/cloud-services/digital-sovereignty/gc-white-paper-data-sovereignty-public-cloud.html

(8) European Commission. (n.d.). A European strategy for data. https://digital-strategy.ec.europa.eu/en/policies/data-union

(9) World Economic Forum. (2025). Europe’s quest for digital sovereignty.https://www.weforum.org/stories/2025/01/europe-digital-sovereignty/