Part 8: Defence and Foreign Policy - part of The Country That Works For You series ← 7. Fiscal Framework · Series index · Next → 9. Social Security
The Question the UK Has Not Answered
The UK has been making foreign and defence policy for seventy years on the assumption that the answer was obvious. The US would underwrite the Western security architecture. NATO would provide the framework. The UN would provide the legitimacy. The pound would provide the financial depth. The result was a country that never had to decide what it was actually for, only what it was against.
That architecture is gone. Not in theory, not in some future projection, but now. The US security guarantee has been revealed as conditional in a way that no post-war British government has had to plan around. NATO is intact as a legal entity but the eastern flank is being defended by Europeans who cannot be sure Washington will show up. The UN is gridlocked. The financial depth exists but the credibility to use it is constrained by the fiscal position described in Part 7 of this series.
So the UK has to answer a question it has avoided for seven decades: what are we actually for?
The answer has to be specific, not aspirational. It is not "global Britain." It is not "a force for good." It is a list of specific interests, specific geographic positions, specific capabilities, and specific costs. That is what this post works through.
The Real Interests
The Gulf
The Gulf matters to the UK for one reason that is worth stating plainly: oil. Not because the UK runs on its own oil, it does not. But because the global oil price is set in the Gulf, and the global oil price determines the cost of everything else. Every litre of diesel, every barrel of the petrochemical feedstock that underpins modern medicine and agriculture, every flight fuel price, every shipping cost flows from a market that the Gulf shipping lanes keep functioning.
The Strait of Hormuz is the chokepoint. Roughly 20 % of global oil flows through it. The closure that happened in February 2026, described in the Situation Assessment, was not a drill. It was a demonstration that the security architecture the UK has relied on can break, and did.
The UK has no independent Gulf security architecture. It has been a beneficiary of the US security guarantee to the Gulf states since the Carter Doctrine of 1980. That guarantee is now more explicitly conditional than at any point in that period. The UK does not have the naval assets to secure Hormuz independently. No country does. It is a two-carrier problem and the UK has one functional carrier.
What the UK can do: maintain a persistent naval presence in the Gulf at sustainable cost, build bilateral security relationships with Gulf states that are not entirely dependent on Washington, and treat the Hormuz shipping lane as a Tier 1 strategic interest rather than a secondary concern. The cost of a sustained Gulf deployment is real - a credible forward presence requires one to two major surface combatants with enabler support, at an estimated annual cost of £200–400m per year in incremental operating expenditure on top of baseline. This figure belongs inside the programme's stated £10–15bn/year additional defence envelope. The cost of not having a Gulf presence is higher, and it is paid in fuel prices.
NATO Eastern Flank
The Baltic states and Poland are the geography of maximum risk in a European land conflict. Russian ground forces that could threaten NATO territory are already positioned in Kaliningrad and western Russia. The Baltic states have small populations and small armies. They cannot defend themselves without NATO.
The UK has committed to NATO's eastern flank. The deployment of British troops to Estonia as part of NATO's enhanced Forward Presence is real. It is also insufficient to deter a serious Russian incursion, and everyone in NATO's command structure knows it. The current deployment is a tripwire: if Russia attacks, British soldiers die. That is the deterrence mechanism. It is not a comfortable one.
The honest assessment: the UK cannot defend the Baltic states alone, and it should not pretend otherwise. What it can do is contribute a meaningful share of whatever NATO decides is the necessary deterrent posture, and push for the rest of NATO to actually resource the commitments it has made. The 2 % of GDP spending target is not arbitrary. It is the floor of what the alliance agreed is necessary to maintain credible deterrence. The UK is not currently spending2 % of GDP on defence. The gap between the commitment and the reality is the structural problem.
The threat model that underlies this assessment is as follows. Russia's ground force advantage in the European theatre is substantial: it can deploy from Kaliningrad and western Russia into the Baltic states with armoured formations that the Baltic countries' own small armies cannot counter at scale. NATO's enhanced Forward Presence (eFP) battlegroups - roughly 1,000 troops per Baltic state - are tripwire forces, not combat-capable defensive formations at the scale required to defeat a serious Russian incursion. The credible deterrence threshold, as assessed by NATO's military command and by open-source defence analysts, requires something closer to a full division-scale presence (10,000–15,000 troops) in each of Estonia, Latvia, and Lithuania, backed by pre-positioned equipment and assured logistics chains. The gap between the current eFP tripwire and the credible deterrence posture is therefore significant. UK deployment to Estonia fills a portion of that gap, but only a portion: the honest assessment of the UK's Baltic deterrence contribution is that it makes the tripwire more credible and raises the political cost of Russian miscalculation, without by itself closing the force-level gap that a full deterrence posture requires.
What happens if the UK walks away from the eastern flank: NATO's eastern deterrence is weakened, the Baltic states lose the tripwire that makes their coverage credible, and the message to Russia is that the UK is not a serious security partner. The cost of that signal is paid across the entire alliance.
The North Atlantic
The North Atlantic is the undersea corridor through which a significant portion of global trade and, critically, the communications cables that carry internet traffic flow. It is also the operating area for the UK and US submarine fleets, including the nuclear deterrent.
The submarine question is the sharp end of the North Atlantic interest. The UK's nuclear deterrent is delivered by nuclear-powered submarines. The US ballistic missile submarine fleet operates in the Atlantic. The anti-submarine warfare capacity that protects both is a capability the UK has been incrementally running down.
The SSBN (Ship, Submarine, Ballistic Nuclear) programme is the centrepiece of the UK's strategic deterrent. It is also one of the most complex industrial programmes in the world. The Astute-class attack submarines that provide the escort and deterrence mission are capable but the production rate is slow and the maintenance demands are high. The UK's submarine-building capacity is concentrated at Barrow-in-Furness and is running at the limit of what the industrial base can sustain.
What happens if the UK walks away from the North Atlantic: the undersea cables that carry roughly 95 % of global internet traffic become more vulnerable to state and non-state interference. The nuclear deterrent becomes more exposed. The SSBN patrol routes become more predictable. None of these outcomes are in the UK's interest.
The Nuclear Deterrent
The nuclear deterrent deserves its own section because it is the one capability the UK cannot replicate and cannot do without.
The logic is simple and brutal. The UK cannot field a conventional military large enough to deter Russia, China, or any other major power from calculating that they could win a conventional conflict. The budget does not exist. The population does not exist. The industrial base does not exist. The nuclear deterrent is the one capability that makes the cost of attacking the UK and its allies unacceptably high for any rational actor.
The cost is real. The continuous at-sea deterrent (CASD) requires at least one nuclear-powered submarine on patrol at all times, carrying the Trident missile system. The programme cost over its lifetime runs to tens of billions of pounds. The renewal of the Trident system, the Dreadnought-class submarines, the infrastructure at Faslane and Aldermaston, the specialist workforce: all of it is expensive and all of it is non-negotiable from a strategic standpoint.
The alternatives: nothing viable has been proposed that provides the same deterrent effect at lower cost. France's independent nuclear force is smaller and more exposed. A US umbrella without UK-owned weapons would mean the UK has no independent deterrent and no independent decision-making authority over nuclear use. That is not a position the UK has been in since 1968, and the strategic cost of entering it would be higher than the cost of maintaining what exists.
The honest assessment: the nuclear deterrent is the one area of UK defence where spending is not justifiable on cost-effectiveness grounds alone. It is justifiable on strategic necessity grounds. Those grounds are real.
The Simultaneous Constraint: The Problem the Interest Hierarchy Does Not Solve
The interest hierarchy - Gulf, NATO eastern flank, North Atlantic, nuclear deterrent - is the right framework for thinking about priorities. But it contains an unexamined assumption that becomes a problem in practice: the assumption that the UK faces these interests sequentially, not simultaneously.
The real risk scenario is simultaneous. A Gulf crisis (Hormuz disruption, Iranian escalation) requires submarine escort and naval presence. A NATO eastern flank crisis (Russian incursion into the Baltic) requires the army deployment and air support. A North Atlantic crisis (state actor anti-submarine warfare threat, cable vulnerability) requires the submarine fleet on patrol. A nuclear deterrent patrol requirement requires at least one SSBN on station at all times. All four can be active at the same time. They are not sequential contingencies. They are concurrent.
The problem is that the UK's submarine fleet - the Astute-class attack submarines - cannot be in all four places at once. The fleet has seven operational Astute-class submarines. One is always on nuclear deterrent patrol (CASD). That leaves six for everything else: Gulf escort, North Atlantic ASW, contingency operations. The math does not work for a simultaneous multi-theatre scenario. Neither does the surface fleet, which is why the carrier availability problem (one of two carriers available at any given time) is not just a logistics issue - it is a strategic constraint.
The interest hierarchy as described does not solve this problem. It names the priorities but does not address the capacity gap. The resolution requires acknowledging it explicitly: the UK does not have the submarine or naval capacity to cover all four tiers simultaneously in a high-intensity scenario. The answer is not to pretend otherwise. It is to make the force planning assumption explicit: the programme must design for a scenario where the first two tiers (Gulf and NATO eastern flank) are prioritised in concurrent operations, and the North Atlantic and nuclear deterrent requirements are maintained as invariant floor requirements. Everything else is secondary.
This means accepting that in a simultaneous multi-theatre scenario, the UK will not be able to provide the full response to all four tiers. The force planning question is: which tier do you give up? The answer this programme proposes is: none of the four tiers is given up in planning assumptions, but the realistic force size means the response to a simultaneous scenario is necessarily constrained. The programme should say this directly rather than allowing the gap to be hidden behind the interest hierarchy.
The Military Capacity Reality
The UK says it spends 2.5 % of GDP on defence by 2027. The Situation Assessment in Part 1 of this series described the gap between that commitment and the actual trajectory. This section is about what that gap means in practice.
What the UK Actually Has
The UK armed forces are a high-readiness, small-force model. The army is approximately 73,000 regular troops. That is not a large army by historical standards or by comparison with peer competitors. It is a army designed for expeditionary operations, not for sustained high-intensity continental warfare.
The Royal Navy operates two aircraft carriers, but only one is typically available at any given time because of maintenance cycles and crew training requirements. The fleet is stretched across NATO commitments, Gulf deployments, and the nuclear deterrent patrol obligations. The Type 45 destroyers are excellent ships but have had availability problems with their propulsion systems. The frigate fleet, now the Type 31 and Type 23 mix, is smaller than the operational requirement calls for.
The Royal Air Force operates the F-35 Lightning II, a genuine fifth-generation capability, but the fleet is small. The Typhoon fleet is capable but aging. The maritime patrol aircraft (P-8 Poseidon) fleet is newer and necessary for North Atlantic anti-submarine warfare, but numbers are limited.
The equipment readiness problem is real and documented. The National Audit Office has repeatedly reported that the equipment availability rates for major platforms are below what the operational commanders say they need. This is not a partisan issue. It is a consequence of procurement programmes that have run over budget and late, reducing the number of platforms available at any given time.
Recruitment and Retention
The UK armed forces have a people problem that is at least as serious as the equipment problem.
Recruitment targets are being missed. Retention is the more acute issue: the skilled personnel who make the equipment work are leaving at rates that the services cannot sustain. The Royal Navy has particular difficulty retaining maritime engineers and weapons specialists. The army has difficulty retaining the senior non-commissioned officers who hold the institutional knowledge. The RAF has difficulty retaining pilots.
The causes are structural: pay that has not kept pace with inflation, housing conditions that are not competitive with civilian alternatives, deployment patterns that put extreme pressure on families, and a civilian labour market that is actively recruiting from the same pools. The government has announced pay awards and improved conditions. They are necessary but not sufficient. The recruitment and retention crisis did not build up overnight and it will not be solved overnight.
The Procurement Problem
The Type 31 frigate programme is the example that illustrates the problem better than any other.
The original plan was for nine Type 31 frigates at a cost of approximately GBP 250 million per ship. The requirement was for an affordable, exportable light frigate that could fill the numbers gap in the Royal Navy fleet. The programme has since moved. The unit cost has increased significantly. The export market has not materialised. The ships are being built but the question of whether they are the right answer for the capability gap they were meant to fill is increasingly contested.
The honest assessment: the Type 31 is a competent light frigate. It is not the answer to the high-intensity anti-submarine warfare requirement in the North Atlantic or the Gulf escort requirement. Those missions need different capabilities. The risk is that the procurement system, under pressure to demonstrate value for money, produces a ship that is affordable on the unit cost metric but insufficient for the operational requirement. That is a false economy.
The broader procurement problem is systemic. The UK has a history of cancelling and restarting major programmes, of specifying requirements that change mid-programme, and of not maintaining industrial investment in critical capabilities. The result is a set of platforms that arrive late, over budget, and sometimes in numbers that do not match the original requirement. The Fiscal Framework post (Part 7) describes the constraint this creates. There is no easy fix. It requires a procurement culture change that is harder to achieve than any individual programme decision.
The Defence-Industrial Link
Part 4 of this series (Industrial Strategy) described the case for domestic manufacturing capacity as a strategic asset rather than a commercial preference. That argument applies with full force to defence.
The UK cannotoutsource its national security. A country that depends on foreign suppliers for its munitions, its specialist steel, its electronics, and its shipbuilding capacity is a country that has outsourced the ability to sustain a prolonged conflict. The supply chain disruptions of 2020 to 2025 demonstrated this in commercial form. The lesson for defence is identical.
The practical implication: procurement policy should have a domestic content requirement for critical capabilities. Not across the board, not as a general preference for expensive domestic suppliers over efficient foreign ones, but specifically for the capabilities where dependency creates strategic risk. Munitions. Specialist steel. Shipbuilding. Submarine components. These are not areas where the UK should be dependent on a single foreign supplier with no alternative.
The Type 31 question again: the programme was sold partly on its export potential, which required a design that was competitive internationally. That constraint shaped the specification in ways that may not perfectly match the UK's own operational requirements. The lesson is that export competitiveness and domestic operational requirement are not always aligned, and when they conflict, the domestic requirement should win for critical capabilities.
The NATO Question
The2 % commitment is the one metric everyone knows. It is also insufficient as a measure of NATO contribution.
NATO's military requirements are set by the alliance's military command structure and approved by the political leadership of member states. The2 % floor is the minimum, not the target. The UK has signed up to it. The gap between the commitment and the actual spend is a credibility problem.
Beyond the money: the UK's contribution to NATO's eastern flank, its submarine capabilities, its intelligence assets, and its special forces all provide value to the alliance that is not fully captured by the 2 % metric. The honest assessment is that the UK is a meaningful contributor to NATO, but not a leader in the way it was during the Cold War, and not a partner that can be relied on for capabilities it does not actually have.
The question of whether NATO is the right framework for UK defence is worth asking honestly. The answer is that NATO remains the right framework for European collective defence, because no alternative has been built and the costs of building a European defence architecture outside NATO are currently higher than the costs of maintaining the alliance. But the UK's role in NATO has to be realistic. It cannot be the junior partner it has sometimes been post-Brexit, and it cannot pretend to be a leader it does not have the resources to be. The UK should position itself as a serious specialist contributor: submarine expertise, intelligence, special forces, and the nuclear deterrent are the areas where UK contribution is genuinely valuable to the alliance.
Foreign Policy Positioning
The Gulf
The UK needs a Gulf policy that is not entirely dependent on Washington. The Gulf states know that the US security guarantee is conditional. They are already diversifying their security relationships. The UK has existing relationships with Saudi Arabia, the UAE, Oman, and Bahrain that are not just about arms sales. They include intelligence sharing, training, and bilateral security agreements.
The practical recommendation: treat the Gulf as a Tier 1 foreign policy interest. Send a senior minister there regularly. Maintain the naval presence. Do not treat it as a US appendage relationship that the UK tags along on. The Gulf states will increasingly be making their own security calculations. The UK should be in the room making those calculations with them.
The EU
The UK's relationship with the EU on foreign and defence policy is complicated by Brexit. The EU has developed its own defence industrial base, its own defence procurement frameworks, and its own foreign policy mechanisms. The UK is not inside them.
The honest assessment: this is a loss. The EU's foreign policy mechanisms are not as capable as NATO's for hard security, but they are the framework through which European states coordinate on sanctions, diplomatic positioning, and the broader exercise of civilian power. The UK being outside those mechanisms means it has less influence over European foreign policy than it did before 2020.
The practical recommendation: seek structured cooperation agreements with the EU on foreign policy and defence industrial issues. Not membership of the EU's political structures, but working arrangements that give the UK influence without requiring the legal framework of membership. The EU needs the UK's intelligence capabilities and military assets. That is leverage.
The US
The post-Trump US is not the US of the post-war period. It may be the US of the transactional period, where alliances are maintained only when they are perceived to serve immediate US interests. That is a different security environment for the UK.
The practical recommendation: maintain the relationship, invest in the bilateral ties that survive changes of administration, but do not build UK defence policy around the assumption that the US will show up. Plan for a world in which the US is a partner when it suits it and an absence when it does not. That is not pessimism. It is the realistic planning assumption.
The Global South
The UK has limited influence in the Global South as a standalone economic actor. It is not large enough to offer the trade relationships that the EU, the US, or China can offer. But it has particular assets: the English language, the Commonwealth connections, the BBC's global reach, the alumni networks of UK universities, and the financial services centre in London.
The honest assessment: these are soft power assets, not hard power ones. They provide influence in specific countries and specific contexts. They do not provide a global power position. The UK should use them honestly, not pretend they amount to something larger.
What This Costs Versus What Inaction Costs
The total additional defence spending required to close the gap between current trajectory and the 2% commitment is in the range of GBP 10 billion to 15 billion per year at current prices. That is real money. It is also the cost of maintaining credible deterrence on the UK's own territory and in the regions it has committed to.
The GBP 10-15bn range is not a rounding exercise. It is derived from: (a) the equipment readiness gap - closing the readiness shortfall across the surface fleet, submarine maintenance, and RAF readiness requires additional procurement budget of roughly GBP 4-6bn per year on top of the current sustainment spend; (b) the recruitment and retention investment - competitive pay, housing improvement, and the personnel pipeline for the specialist skills (maritime engineering, cyber, nuclear) requires roughly GBP 2-3bn per year; and (c) the procurement reform investment - the industrial base at Barrow, Rosyth, and the missile fuel facilities needs capital investment to maintain the nuclear deterrent and submarine programmes, which is roughly GBP 3-5bn per year over the programme life. These figures are directional, not precise, and the programme should commission a full defence spending review to verify them. But the order of magnitude is right.
The cost of inaction is harder to quantify and therefore easier to ignore. It includes: the risk of a Russian calculation that NATO's eastern flank is notcredibly defended, which would require a far more expensive response after a conflict rather than before one; the risk of Hormuz disruption without the naval capacity to contribute to deterrence; the risk of the nuclear deterrent being exposed because the submarine escort fleet is insufficient; and the broader risk of the UK being a spectator in a world where its interests are decided by others.
The fiscal argument against spending more on defence is real. Part 7 of this series (Fiscal Framework) describes the constraint. But the fiscal argument against defence spending is not a free option. It is a bet that the security environment remains stable enough that the UK does not need the capabilities it is not buying. That bet has been losing since February 2026.
What a Government Should Actually Do
The summary is direct:
One, define the specific interests: Gulf shipping lanes, NATO eastern flank, North Atlantic undersea routes, and the nuclear deterrent. These are not negotiable. Everything else is secondary.
Two, resource them honestly. The 2 % commitment is the floor. The UK should spend it and should be clear about what it buys. The gap between commitment and spend is a credibility problem, not just a accounting problem.
Three, fix the procurement system. Not by spending more money on the same broken process, but by fixing the process: stable requirements, longer production runs, domestic content requirements for critical capabilities, and a clear-eyed acceptance that cheap procurement and operationally adequate procurement are not always the same thing.
Four, build the industrial base. This connects directly to Part 4 (Industrial Strategy). The steel, the chemicals, the specialist manufacturing capacity: these are defence capabilities as much as they are commercial ones.
Five, position the UK as a serious specialist partner in NATO, not a fantasist global power and not a passive appendage. The UK has genuine capabilities in submarines, intelligence, special forces, and nuclear deterrence. It should invest in those and be honest about the limits.
Six, run a foreign policy that is not entirely dependent on Washington. The Gulf relationships, the EU working arrangements, the Commonwealth connections: these are assets that require active management, not just rhetoric.
Seven, maintain the nuclear deterrent. It is expensive. The alternatives are worse.
The strategic vacuum described in Part 1 of this series is real. The vacuum does not wait for the UK to fill it. The choices described here are not optional. They are the minimum set of decisions required to maintain a credible national defence posture in a world where the assumptions of the last seventy years have been retired. The UK can make them or it can discover what it is worth when it has not made them. The latter discovery is not comfortable.
Part 8: Defence and Foreign Policy - part of The Country That Works For You series
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