Since 2015, His Majesty’s (HM) Government has released several national security and defence strategies, most recently the 2025 National Security Strategy (NSS) and the 2025 Strategic Defence Review (SDR). Both state that the United Kingdom (UK) must pursue its national security and defence in service of the national interest. Yet, neither document identifies what those specific interests actually are. The NSS, for example, mentions the ‘national interest’ 11 times, but asserts only that these interests will be defined as ‘the long-term security and social and economic wellbeing of the British people’ – a laudable goal, but one that lacks the specificity required for strategic planning.
Meanwhile, the SDR identifies three key roles for British defence policy: firstly, defending the British homeland, the Overseas Territories, and the Crown Dependencies from attack; secondly, deterring and defending in the Euro-Atlantic; and, finally, shaping the global environment. While these are vital operational tasks, they describe how Britain will act, rather than what fundamental interests it is acting to protect.
Ultimately, of course, HM Government’s fundamental duty is to maximise the security, prosperity, and wellbeing of the British people, as the NSS rightly notes. Translating this ambition into practice, however, requires the development of a series of nested national interests. These must look inward before they look outward. Strategic objectives cannot be achieved overseas if the domestic powerbase – comprising civic identity, institutional structures, and the economy – is hollowed out at home. Therefore, Britain’s fundamental interests must be understood as an interconnected chain – building from the human and economic foundations of the country up to the ultimate guarantees of sovereign power.
The following five national interests have been selected because they form an integrated whole, based on the geographic predilection of the British Isles, the scale of the national powerbase, and the prevailing character of the contemporary international order.
Five national interests
1. National cohesion and civic unity
A fractured society is an acute national security vulnerability. In an era of ideological conflict and political warfare, adversaries do not just target military infrastructure; they exploit domestic social, cultural, and political fault lines to paralyse a state’s decision-making apparatus. While pluralism of thought is a democratic norm, a fundamental lack of national cohesion erodes the shared civic identity required to withstand protracted crises. If a population believes it shares no common destiny, its collective will to resist foreign coercion may decline. Cultivating national self-confidence and civic unity is therefore a strategic necessity; without it, the British public remains highly susceptible to cognitive manipulation and subversion by hostile foreign states.
2. A dynamic and resilient national powerbase
Building upon this internal solidarity, the UK must cultivate a dynamic and resilient national powerbase. In the 21st century, relying on strategic competitors for energy supplies, key commodities, advanced manufacturing capabilities, and critical infrastructure is a severe vulnerability. Britain must also refuse to be dependent on hostile powers for its technological and research base. A core national interest is securing domestic or tightly allied control over next-generation technologies, such as Artificial Intelligence (AI), fusion power, quantum computing, and advanced maritime and aerospace manufacturing. Additionally, the UK must protect and promote the City of London’s position as a global command centre while also building capacity to engage in economic statecraft, including economic sanctions, capital controls, and access to British financial markets as coercive weapons to punish adversaries and to reward compliance.
3. A zone of denial
As an archipelagic nation dependent on open seas, undersea infrastructure, and orbital spaces for the transit of food, energy, manufactured goods, and information, the UK must do everything in its power to secure the communication lines that supply its national powerbase. Without the continental scale of a superpower, Britain lacks the mass required for absolute global sea or space control, so British strategy must focus on a strategy of denial. Geographically, this requires securing not just immediate Euro-Atlantic approaches – such as the Northern Gap and the Strait of Gibraltar – but also the critical maritime arteries and strategic chokepoints connecting the Euro-Atlantic to the Indo-Pacific, including the Persian Gulf, the Bab al-Mandeb Strait, and the Strait of Malacca. It must also focus on space to protect British orbital assets and deny space-based advantages to adversaries. Ultimately, this global reach is essential to counter Russian revisionism, disrupt a consolidating Chinese-Russian axis in Eurasia, and help protect Britain’s most vital allies and partners – including those in Europe, but also the United States (US), Australia, Canada, and Japan.
4. Strategic indispensability to key alliances
Alliances are not friendships or communities of values. Rather, they hold three functions: firstly, to deter adversaries from attacking countries or regions that the UK deems essential to its own wellbeing; secondly, to dissuade allies from taking actions that are detrimental to British interests; and thirdly, to act as force multipliers for the UK’s own powerbase. This is why the North Atlantic Treaty Organisation (NATO), above all else, is central to the defence of the British Isles. Part of Ernest Bevin’s rationale for forging NATO was to keep the Soviets out of Western Europe, smother geopolitical competition in Western Europe, and draw in US power so as to reduce the cost of the endeavour to the British people. Likewise, AUKUS is also increasingly central to Britain’s defence: it deters the People’s Republic of China (PRC) and Russia; it spreads the cost of developing expensive next-generation nuclear and conventional technologies; and it amplifies British power by combining forces with Australia and the US.
5. Sovereign control of the nuclear escalatory ladder
While alliances multiply British power, they cannot replace the ultimate link in the chain: sovereign control over nuclear escalation. With the advent of nuclear weapons in 1945, a country had to possess nuclear capability to be taken seriously as a great power. Without it, a state lacks the ultimate sovereign guarantor of its continued freedom. That is why HM Government has maintained a Continuous At-Sea Deterrent (CASD) with a guaranteed second strike delivery system since 1969. However, possession of such awesome destructive power is not enough: in an era where several adversaries are nuclear-armed, the UK needs sovereign control over its escalatory response. It is no longer enough to possess a single strategic weapons system; if Britain is to do more to underwrite NATO, it needs to be able to meet potential nuclear-armed rivals symmetrically, and provide a flexible response – an imperative that now demands the acquisition of sub-strategic nuclear weapons.
Conclusion
As the UK starts to look towards a new cycle of strategic assessment, it should begin to think harder about its fundamental interests. Over the past few decades, British strategic reviews have too often been budget-led or threat-led. This has resulted in reactive policies that primarily respond to the crises of the day, rather than shaping the world surrounding the UK to the advantage of the nation. By structuring future defence and security strategies through fundamental national interests, policymakers can ensure that resources are allocated proactively, capabilities are developed purposefully, and that Britain remains secure and prosperous in an increasingly confrontational world.
What do you think? What is Britain’s most fundamental national interest? Vote in our poll!
James Rogers is Co-President (Research) of the Council on Geostrategy.
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Thanks for saying Britain and British in this context, not*just* "UK". People aren't compelled to defend acronyms, but rather nations.