BISC Research Paper
By Eva Sula
1. Introduction: Why JEF Matters Now
The Joint Expeditionary Force deserves closer strategic attention because the security environment for which it was designed has become more central to European defence. Northern Europe is no longer a peripheral flank, a collection of separate national defence problems, or a region that can be analysed through distinct Baltic, Nordic, Arctic and North Atlantic lenses. Russia’s full-scale invasion of Ukraine, Finland’s accession to NATO in April 2023, Sweden’s accession in March 2024, the growing vulnerability of critical undersea infrastructure, and the increasing military and political importance of the High North have changed the strategic map of Europe. These developments have made the operating environment across Northern Europe more connected, more contested and more immediate.
JEF matters because it sits across this connected geography. Its core areas of interest are the High North, the North Atlantic and the Baltic Sea region, and these areas increasingly form one strategic system rather than three separate theatres. Reinforcement routes, maritime access, energy flows, data cables, naval activity, air defence, intelligence collection, host-nation support and escalation management are all tied together across this space. A disruption in the Baltic Sea can have implications for Nordic security, energy resilience and allied decision-making. A crisis in the High North can affect North Atlantic access, reinforcement timelines and the credibility of deterrence further south. The practical security problem is therefore not only how to defend individual territories, but how to understand and manage a connected regional operating environment.
This matters especially after Finland and Sweden joined NATO. Their accession strengthened NATO’s northern posture, changed the military geography of the Baltic Sea and created new opportunities for integrated regional defence planning. It also increased the importance of frameworks that had already built habits of cooperation among the relevant states before full NATO integration was complete. JEF is one of those frameworks. It brought together the United Kingdom, Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway and Sweden around a shared regional security focus before all of its members sat under the same NATO Article 5 umbrella. In that sense, JEF was not made relevant by NATO enlargement alone, but NATO enlargement made its underlying logic more visible.
The deterioration of the European security environment has also changed what regional defence cooperation must be able to do. The challenge is no longer limited to conventional deterrence, although conventional deterrence remains essential. It includes hybrid activity, maritime disruption, cyber pressure, information operations, energy security, sabotage risks, military signalling, rapid consultation and the protection of critical infrastructure. The Balticconnector incident in 2023, subsequent damage to undersea cables in the Baltic Sea, and wider concern about hostile or ambiguous activity against seabed infrastructure have reinforced the point that regional security now operates across thresholds. States require mechanisms that can support political alignment, military visibility and coordinated response before a situation becomes a clear Article 5 crisis.
JEF’s relevance lies in this space between national action and alliance-wide mobilisation. NATO remains the foundation of collective defence for its members, and JEF does not replace it. The value of JEF is different. It provides a flexible framework for like-minded states to consult, exercise, signal, coordinate and, when required, act together in the region where their interests most directly overlap. Its usefulness comes less from institutional weight than from political trust, geographic coherence and the ability to move quickly. In a security environment where warning time may be short and ambiguity may be deliberate, these qualities matter.
This distinction between institutional weight and operational usefulness is central to understanding JEF. Large institutions provide legitimacy, scale, planning depth and collective defence guarantees. Smaller regional frameworks can provide speed, focus, familiarity and practical responsiveness. The two should not be treated as competitors. In the Northern European context, JEF is best understood as a practical defence layer that complements NATO by strengthening regional habits of cooperation, improving readiness among closely connected states and creating options for early coordination. Its importance lies not in being a substitute for larger institutions, but in helping ensure that those institutions are supported by regional preparedness before crisis conditions escalate.
For that reason, JEF deserves analysis beyond official statements and summit language. Its significance is not only that ten countries cooperate under a UK-led framework. Its significance is that those countries sit across one of Europe’s most strategically exposed and increasingly integrated regions, and have developed a format that reflects the reality of how security problems now emerge there. The question is therefore not simply what JEF is, but why it works and what its experience reveals about the future of regional defence cooperation in Europe.
2. What JEF Is and What It Is Not
The Joint Expeditionary Force is a UK-led defence framework of ten Northern European countries: the United Kingdom, Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway and Sweden. It is focused on the High North, the North Atlantic and the Baltic Sea region, and its purpose is to provide a flexible framework through which like-minded states can consult, train, exercise, signal and, where politically agreed, generate military options together.
JEF is not a standing army, a separate alliance or a replacement for NATO. It is better understood as a framework of prepared relationships, habits, procedures and forces that can be brought together when participating nations decide to act. Its value lies partly in what it does not try to become. It does not carry the full institutional burden of NATO, does not require all European states to agree, and does not need to turn every activity into a permanent structure. This gives it a degree of responsiveness that is difficult to achieve in larger organisations, while still allowing it to remain coherent with NATO planning and allied deterrence.
The origins of JEF go back to the United Kingdom’s post-Afghanistan and post-Iraq effort to rebuild a rapidly deployable, joint, high-readiness force that could operate with close partners. The concept was first conceived in 2012 and developed from the earlier UK Joint Rapid Reaction Force. The multinational JEF was launched in the context of the 2014 NATO Wales Summit, where the United Kingdom and six initial partners moved towards a framework built around high-readiness forces, interoperability and rapid response. Denmark, Estonia, Latvia, Lithuania, the Netherlands, Norway and the United Kingdom formed the original core, with Finland and Sweden joining in 2017 and Iceland joining in 2021.
This evolution matters because JEF was not created only as a Baltic or Nordic defence format. Its initial logic was broader: to create a pool of high-readiness forces that could respond to crises with like-minded partners, including in support of NATO, the United Nations or other international requirements. Over time, however, the deterioration of the European security environment and Russia’s aggression against Ukraine pulled JEF’s practical centre of gravity more clearly towards Northern Europe. What began as a flexible expeditionary framework has become increasingly important as a regional defence instrument in the area where its members’ security interests most directly overlap.
The relationship with NATO is central to understanding JEF correctly. NATO remains the foundation of collective defence for JEF members that are allies, and JEF does not change the legal or strategic importance of Article 5. Its role is complementary. It can support deterrence and defence by improving readiness, interoperability and regional coordination among states that already share geography, threat perceptions and military habits. It can also operate in situations below the threshold of NATO’s full collective defence machinery, where political signalling, maritime presence, surveillance, rapid consultation or limited military activity may be required before a crisis becomes clearly defined.
This makes JEF particularly relevant in the current phase of European security. The question facing Europe is not only whether NATO exists as the central guarantee of collective defence, but whether European allies have enough practical mechanisms to act early, coherently and regionally when warning signs emerge. The United States remains central to NATO, but the political debate around burden-sharing, the pressure on American attention across theatres, and the expectation that European allies carry more responsibility for their own regional security all increase the importance of frameworks that can generate European action without weakening NATO. JEF fits into this space because it strengthens the European pillar of allied deterrence while remaining explicitly aligned with NATO rather than positioned against it.
JEF also has significance because it bridges a regional security problem that does not always fit neatly into formal command boundaries. NATO command arrangements are adapting to the accession of Finland and Sweden, the strategic importance of the High North and the need to connect the North Atlantic, Nordic region, Baltic Sea and eastern flank more effectively. Even as NATO structures evolve, the operational reality remains that Northern European security crosses maritime, air, land, cyber and infrastructure domains, and connects areas that can be divided administratively even when they are strategically interdependent. JEF cannot solve NATO command architecture, but it can help create political-military coherence across the same arc of geography by building habits of consultation and regional situational awareness among the states most directly affected.
This is especially visible in the maritime domain. Recent JEF activity has increasingly reflected the vulnerability of undersea infrastructure, the importance of maritime routes, the threat posed by Russia’s shadow fleet and the need for persistent surveillance across the Baltic Sea, North Atlantic and High North. Nordic Warden and related JEF response activity show how the framework can be used to support monitoring, coordination and deterrence around critical undersea infrastructure. The reported move towards a more integrated JEF maritime force further underlines the point that JEF is no longer only a political consultation format or an exercise framework. It is becoming a practical vehicle for building readiness in the maritime approaches that connect Northern Europe to allied reinforcement, trade, energy and data flows.
The fact that JEF is UK-led is also important. The United Kingdom remains one of Europe’s most capable military actors, with particular weight in maritime, expeditionary, intelligence, nuclear, special operations and high-readiness forces. In JEF, the UK provides framework-nation leadership without requiring the structure to become a UK-only instrument. This balance gives smaller and medium-sized states access to a broader operational framework while allowing them to shape regional priorities from their own geographic perspective. For Estonia, Latvia and Lithuania, JEF strengthens the connection between Baltic security and wider Northern European deterrence. For Norway, Iceland and the United Kingdom, it reinforces the North Atlantic and High North dimension. For Finland and Sweden, it builds on Nordic-Baltic cooperation and supports their integration into allied defence structures.
JEF should therefore be understood as a defence framework built around practical usefulness rather than institutional completeness. Its strength lies in the combination of political trust, military familiarity, shared regional exposure and enough flexibility to act without waiting for every security problem to become an alliance-wide decision. It is not the answer to every European defence challenge, and it cannot substitute for NATO’s command structure, force planning or collective defence guarantees. Its importance is that it helps fill the space between national action and alliance-level mobilisation, where many contemporary security problems first appear and where early coordination can shape deterrence before escalation becomes harder to manage.
3. The Assumption That Should Not Work
Viewed from a distance, the Joint Expeditionary Force appears to bring together a combination of states that should be difficult to organise into a coherent defence framework. Its members vary significantly in size, geography, military capability, strategic priorities and political traditions. Some are major military powers with global responsibilities, while others are small states focused primarily on territorial defence. Some maintain substantial naval capabilities and expeditionary experience, while others concentrate largely on homeland defence and regional security. Some sit directly on NATO’s eastern flank, while others are separated from Russia by geography and distance.
Conventional assumptions about defence cooperation would suggest that such diversity creates friction rather than effectiveness. Different threat perceptions can produce different priorities. Different force structures can complicate interoperability. Different political cultures can slow decision-making. Different strategic horizons can make it difficult to sustain a common purpose. Many multinational defence initiatives have struggled precisely because the participating nations agreed on broad objectives while disagreeing on practical priorities.
JEF has largely avoided this problem. The reason is not that these differences have disappeared, nor that all participating states see security challenges through exactly the same lens. Rather, JEF succeeds because it is built around a shared strategic problem instead of a shared institutional identity. Its members do not need to become strategically identical to recognise that developments in the Baltic Sea region, the High North and the North Atlantic increasingly affect all of them.
The differences between JEF members are substantial. The United Kingdom remains one of Europe’s largest military powers, with global commitments, nuclear capabilities, significant naval forces and a long expeditionary tradition. Norway combines Arctic responsibilities with extensive maritime interests in the North Atlantic. Denmark must balance Baltic and Arctic concerns while maintaining responsibility for Greenland and the Faroe Islands. Finland and Estonia place particular emphasis on territorial defence and resilience against potential Russian aggression. Iceland has no standing armed forces but occupies a strategically significant position in the North Atlantic. The Netherlands brings advanced maritime and expeditionary capabilities while maintaining strong links to broader European security initiatives.
These differences extend beyond military structures. Geography shapes how individual members perceive risk and prioritise resources. For Estonia, Latvia and Lithuania, deterrence is inseparable from the reality of sharing a region with Russia and Belarus. For Norway, security calculations are strongly influenced by Arctic developments and North Atlantic access routes. For the United Kingdom, regional security must be balanced alongside global commitments and alliance responsibilities. Finland’s strategic culture has been shaped by its long border with Russia, while Sweden’s defence transformation has reflected both territorial defence requirements and wider regional responsibilities.
Even where threat perceptions broadly align, the practical consequences of those threats often differ. A disruption to maritime traffic in the North Atlantic creates different operational concerns than interference with critical infrastructure in the Baltic Sea. Arctic military activity, hybrid pressure, undersea infrastructure vulnerability, airspace violations and military signalling may all form part of the same strategic picture, yet affect individual members in different ways and at different times.
What makes JEF noteworthy is that these differences have not prevented practical cooperation. In many respects, they have reinforced the framework’s relevance. Because members approach the same regional security environment from different perspectives, they contribute complementary capabilities and viewpoints. Maritime awareness, Arctic expertise, territorial defence experience, expeditionary planning, intelligence cooperation and resilience measures are not distributed evenly across the membership. The framework benefits from this diversity rather than being weakened by it.
This reflects a broader principle often overlooked in discussions about multinational defence cooperation. Effective frameworks do not necessarily require uniformity. They require sufficient alignment around a shared strategic challenge. The Baltic Sea, the High North and the North Atlantic create exactly such a challenge. Although members may prioritise different parts of this geography, none can isolate their own security from developments elsewhere within the wider region. Reinforcement routes, maritime access, energy security, undersea infrastructure, military mobility and deterrence are increasingly interconnected.
The flexibility of JEF is therefore not merely an administrative characteristic. It is one of the reasons the framework functions. Because participation is driven by practical cooperation rather than institutional obligation, members can focus on areas where interests overlap most strongly. The framework does not require complete policy harmonisation or the creation of large permanent structures. Instead, it provides mechanisms through which states with different capabilities and priorities can coordinate when their security interests converge.
This stands in contrast to some larger multinational arrangements where institutional complexity can become a challenge in itself. Larger organisations inevitably carry broader political responsibilities, larger memberships and more diverse strategic perspectives. These characteristics provide legitimacy and scale, but they can also make rapid consensus more difficult. JEF occupies a different space. Its narrower geographic focus and relatively small membership allow it to build trust, familiarity and practical cooperation around a clearly defined regional security environment.
The result is a framework that appears, at first glance, less coherent than many formal institutions but often proves more adaptable in practice. The diversity of its members is not removed or ignored. It is managed through a shared understanding that developments in Northern Europe increasingly affect all participants, even when those effects are experienced differently. JEF works not because its members are identical, but because they recognise that they are connected.
4. Why JEF Actually Works
The success of the Joint Expeditionary Force is often explained through its flexibility, its regional focus or its relatively small membership. While each of these factors contributes to its effectiveness, none fully explains why JEF has remained relevant while many multinational initiatives struggle to move beyond declarations and periodic meetings. The deeper explanation lies in the interaction between geography, trust, responsiveness and practical military cooperation.
JEF works because its members face a common strategic environment, have developed unusually high levels of political confidence in one another, possess mechanisms that support rapid consultation and have repeatedly translated political alignment into operational activity. These characteristics reinforce one another. Geography creates shared interests, trust reduces friction, flexibility accelerates decision-making and practical cooperation strengthens credibility. Together, they produce a framework that is often more effective than its relatively modest institutional structure would suggest.
4.1 Shared Strategic Geography
Geography remains one of the most powerful forces shaping security policy. While technology changes how states communicate, fight and coordinate, geography continues to influence reinforcement routes, military mobility, access to resources, infrastructure resilience and strategic vulnerability. The states participating in JEF are connected by a geography that has become increasingly difficult to divide into separate security regions.
The Baltic Sea, the North Atlantic and the High North are often discussed independently. In operational reality, they form an interconnected system. Maritime traffic moving through the Danish Straits connects the Baltic Sea to the wider Atlantic. Reinforcements destined for Northern Europe depend on secure sea and air routes across the North Atlantic. Arctic developments influence military posture, surveillance requirements and access routes further south. Undersea cables, energy infrastructure and logistics networks cross multiple jurisdictions and operating environments simultaneously.
This interconnected geography has become more visible following Finland and Sweden’s accession to NATO. The Baltic Sea has effectively become a NATO internal operating space, yet its security remains dependent upon developments beyond the Baltic itself. The ability to reinforce Estonia, Latvia or Lithuania is connected to North Atlantic access, Nordic infrastructure, maritime security and the ability to move forces across a wider northern theatre. Likewise, challenges emerging in the High North cannot be isolated from broader allied planning because they influence the same reinforcement and deterrence architecture.
Russia’s military posture reinforces these connections. Activity originating from the Kola Peninsula, Russian naval operations in the North Atlantic, military developments in Kaliningrad, pressure on critical infrastructure and hybrid activity in maritime domains all affect different parts of the same strategic system. Individual JEF members may experience these pressures differently, but they are responding to connected challenges rather than isolated national problems.
JEF benefits from this reality because its membership broadly aligns with the geography itself. The framework was not constructed around abstract institutional ambitions. It emerged around states whose security is increasingly shaped by the same maritime routes, infrastructure networks, reinforcement corridors and deterrence requirements. Geography provides the foundation upon which the other strengths of JEF are built.
4.2 Political Trust
Shared geography alone does not automatically produce effective defence cooperation. Many regions contain states with overlapping security interests but limited ability to coordinate. One of JEF’s most significant strengths is the degree of political trust that exists among its members.
Trust is often discussed as an intangible concept, yet its practical impact on defence cooperation is substantial. Political trust reduces uncertainty regarding intentions, accelerates consultation processes and lowers the barriers to information sharing, planning and coordination. States that trust one another require fewer mechanisms to verify every decision and can move more quickly when circumstances demand action.
The foundations of trust within JEF extend beyond the framework itself. Nordic cooperation, Baltic cooperation, NATO membership, bilateral defence relationships and decades of participation in multinational operations have created a dense network of relationships among political leaders, military organisations and defence institutions. Many JEF members have served together in Afghanistan, Iraq, the Balkans and numerous NATO activities. These experiences create familiarity that cannot be replicated quickly through formal agreements alone.
Trust is reinforced by broadly similar assessments of the security environment. JEF members do not agree on every policy issue, nor do they face identical national circumstances. However, they generally share an understanding of the challenges posed by Russian military behaviour, the importance of maritime security, the value of allied deterrence and the need to protect critical infrastructure and democratic institutions. This alignment reduces the strategic friction that often complicates multinational initiatives.
The result is not consensus on every issue, but sufficient confidence to coordinate effectively when regional security concerns emerge. In practice, this allows JEF to function with a degree of responsiveness that would be difficult to achieve in frameworks where political trust is weaker or strategic priorities are more divergent.
4.3 Speed and Flexibility
One of the most distinctive features of JEF is its ability to maintain relevance without continuously expanding its institutional structure. Many multinational initiatives respond to new challenges by creating additional layers of governance, permanent bodies or increasingly complex procedures. While such developments can improve coordination in some circumstances, they can also reduce responsiveness.
JEF has largely avoided this dynamic. Its design allows participating nations to coordinate activities without transforming every requirement into a permanent institution. This gives members the ability to adapt their cooperation to changing circumstances while retaining a clear strategic focus.
The value of this flexibility has increased as the security environment has become more dynamic. Contemporary security challenges frequently develop below the threshold of conventional conflict. Hybrid activity, maritime incidents, infrastructure disruption, cyber operations and strategic signalling often require rapid consultation before formal crisis mechanisms are activated. Frameworks capable of supporting early coordination possess advantages that are not always visible in traditional force structure comparisons.
Flexibility also allows JEF to accommodate differences among its members. Not every nation contributes in the same way to every activity, nor is complete uniformity required. The framework allows states to participate according to their capabilities, interests and circumstances while remaining part of a broader regional effort. This approach preserves cohesion without demanding unnecessary standardisation.
The importance of speed should not be underestimated. Security challenges in Northern Europe increasingly evolve on compressed timelines. Decision-makers may have limited warning, incomplete information and significant political uncertainty. Under such conditions, mechanisms that support rapid consultation and practical coordination become strategically valuable in their own right.
4.4 Operational Reality
The ultimate test of any defence framework is whether it can translate political intent into practical activity. JEF’s credibility comes not from declarations about cooperation, but from a growing record of exercises, deployments, consultations, response options and regional security initiatives.
Since reaching full operational capability, JEF has conducted a wide range of exercises across maritime, land and air domains. These activities have strengthened interoperability, improved familiarity among participating forces and provided opportunities to test concepts under realistic conditions. More importantly, they have created operational habits that can be relied upon during periods of uncertainty.
JEF has also demonstrated an ability to respond to changing security circumstances. Following Russia’s invasion of Ukraine, member states intensified cooperation, strengthened regional deterrence measures and increased coordination across the northern theatre. More recently, concerns regarding critical undersea infrastructure, maritime security and the activities of Russia’s shadow fleet have prompted practical initiatives that go beyond traditional military exercises.
The development of Nordic Warden and increasing attention to maritime domain awareness illustrate this evolution. The protection of undersea infrastructure, energy networks, communication links and maritime approaches has become an increasingly important aspect of regional security. JEF provides a framework through which participating nations can coordinate responses to challenges that cross national boundaries and do not fit neatly within traditional military categories.
Operational relevance also extends to capability development and readiness. European allies face growing pressure to strengthen defence industrial capacity, improve resilience and reduce vulnerabilities associated with long procurement timelines and supply-chain dependencies. While JEF is not a procurement organisation, it provides a mechanism through which members can identify common requirements, develop shared understanding and align priorities within a shared operating environment.
This practical orientation ultimately explains why JEF has maintained momentum. It is not sustained by institutional expansion or political symbolism alone. It remains relevant because it addresses real security challenges experienced by its members and because it has repeatedly demonstrated an ability to convert shared concerns into practical cooperation. Geography may provide the foundation, but operational activity is what gives the framework credibility.
5. What Others Can Learn from JEF
The wider lesson of the Joint Expeditionary Force is not that every region should copy its structure. JEF works because of specific geography, specific political relationships and specific security pressures. Its value as a model lies less in its institutional form than in the principles behind it. Those principles are relevant beyond Northern Europe because many defence organisations and governments are now trying to solve the same underlying problem: how to create practical military and political cooperation before crisis conditions expose the limits of slower institutional machinery.
The first lesson is that trust must precede structure. Multinational defence cooperation often begins with the assumption that new mechanisms, boards, headquarters or coordination bodies will produce coherence. JEF suggests a different sequence. Structures help when they formalise relationships that already have political confidence, shared expectations and operational familiarity behind them. Without that foundation, additional process can conceal rather than resolve disagreement. With that foundation, relatively light structures can become effective because participating states already understand why they need one another.
The second lesson is that shared interests matter more than institutional design. JEF is not held together by a comprehensive treaty framework or an ambition to become a full-spectrum European defence organisation. It is held together by the fact that its members face connected security challenges across the High North, the North Atlantic and the Baltic Sea region. This gives the framework strategic discipline. It does not need to solve every European defence problem because it is focused on a region where its members have direct interests and practical reasons to cooperate.
The third lesson is that practical cooperation should come before bureaucracy. Exercises, response options, maritime activity, staff-level familiarity, communication habits and common operating procedures often matter more than formal declarations. Defence cooperation becomes credible when personnel, units and decision-makers develop habits that can survive pressure. JEF’s usefulness lies partly in the way it builds these habits without waiting for every question to be resolved at the highest political level.
This lesson is particularly relevant in a period when many European states are trying to rebuild defence capacity after decades of underinvestment. Rearmament alone will not automatically produce usable capability. New platforms, munitions, sensors and command systems will only matter if they can be integrated into joint plans, sustained under pressure and used coherently with partners. JEF shows that regional frameworks can help convert national rearmament into shared operational value by creating a setting in which interoperability, readiness and regional priorities are addressed together rather than separately.
The fourth lesson is that regional frameworks should act as accelerators, not substitutes. JEF strengthens European security when it improves readiness, coordination and deterrence in support of NATO and wider allied objectives. It would become weaker if it tried to replace larger institutions or compete for political attention as an alternative security architecture. Its value is additive. It gives participating states a way to move earlier, think regionally and prepare practically, while remaining anchored in NATO standards, doctrine and collective defence planning.
This accelerator role is increasingly important as European allies are expected to assume greater responsibility for their own security. The issue is not simply the future level of United States engagement in Europe, although American strategic attention is increasingly pulled across multiple theatres. The deeper point is that European states cannot assume that allied reinforcement, industrial supply, munitions availability or political decision-making will move at the speed required by every regional crisis. Frameworks such as JEF help reduce this vulnerability by creating regional habits of preparedness before external support becomes decisive.
The fifth lesson is that small and medium-sized states can shape regional security when the framework is well designed. JEF does not erase asymmetry among its members. The United Kingdom remains the framework nation and provides significant military and political weight. Yet the structure also allows smaller states to bring geographic knowledge, threat understanding, resilience experience and regional urgency into a wider defence setting. For the Baltic states, this matters because it connects their security to the North Atlantic and High North rather than leaving Baltic defence as an isolated eastern-flank concern. For Nordic members, it reinforces the link between Arctic, maritime and Baltic security. For the United Kingdom, it provides a practical route to sustained leadership in Northern European defence.
The sixth lesson is that capability habits matter more than communiqués. European defence cooperation often produces strong language about interoperability, resilience and shared responsibility, but the operational gap remains when national systems, procurement choices, information-sharing practices and command arrangements do not connect. JEF’s future relevance will depend on whether it continues to build practical habits across the domains where regional security is now contested: maritime surveillance, air and missile defence, cyber resilience, critical infrastructure protection, electronic warfare, unmanned systems, logistics, military mobility and shared situational awareness.
This is also where JEF offers a useful reminder to its own members. The framework works because it was built around trust, geography and practical cooperation. Those conditions cannot be taken for granted. In the current European environment, many states are under pressure to look inward, prioritise national procurement, protect national industrial interests and rebuild capabilities at speed. Those pressures are understandable, but they can also produce fragmentation if regional cooperation is treated as secondary to national rearmament. JEF’s original logic remains valuable precisely because it offers a way to connect national effort to shared regional purpose.
The broader lesson is therefore not that JEF is a finished model. It is that defence cooperation becomes most useful when it is rooted in real strategic exposure, supported by political trust and tested through practical activity. Larger institutions remain essential for collective defence, legitimacy and scale, but regional frameworks can help close the gap between warning and response. In an era of ambiguity, compressed decision timelines and contested infrastructure, that gap is often where deterrence is either strengthened or weakened.
6. Challenges Ahead
JEF works because it is focused, trusted and flexible. Those same strengths also create vulnerabilities. A framework that depends on political attention, voluntary participation and practical coordination can lose momentum if members become distracted, if national priorities diverge, or if its relationship with NATO becomes unclear. The challenge for JEF is therefore not only to preserve what has made it effective, but to develop enough structure to matter in crisis without becoming so institutionalised that it loses its agility.
The first challenge is sustaining political attention. JEF has benefited from a period in which Northern European security has become visibly urgent. Russia’s war against Ukraine, Finland and Sweden joining NATO, repeated incidents involving critical undersea infrastructure, and concern over Russia’s shadow fleet have all reinforced the relevance of regional cooperation. The risk is that attention remains high only while events are acute. Defence frameworks often struggle not during moments of crisis, but in the periods between crises when budgets, procurement, domestic politics and competing priorities begin to dilute focus.
This challenge is intensified by the fact that most European states are rebuilding defence capacity after decades of underinvestment. Increased defence spending is necessary, but higher spending does not automatically produce regional capability. The United Kingdom faces difficult choices over force structure, readiness, personnel, industrial capacity and global commitments. Nordic and Baltic states are also expanding capabilities while managing infrastructure, manpower and procurement constraints. The Netherlands, Denmark and Norway bring important capabilities, but they too face the challenge of converting spending commitments into usable, deployable and sustainable force packages. JEF can support regional coherence, but it cannot compensate for insufficient readiness, hollow force structures or delayed procurement.
The second challenge is avoiding duplication with NATO. JEF’s value depends on complementarity. Official JEF policy documents repeatedly state that the framework is designed to complement NATO and national response capabilities, using NATO standards and doctrine as a baseline. This alignment is essential because JEF members are now all NATO allies, and any regional defence activity must strengthen rather than complicate alliance planning. If JEF becomes too separate from NATO, it risks creating parallel processes. If it becomes too absorbed into NATO, it risks losing the speed and flexibility that make it useful. The task is to maintain a clear division of labour in which JEF can support early consultation, regional readiness, sub-threshold response and political-military signalling while remaining coherent with NATO deterrence and defence plans.
The third challenge is clarifying the role of JEF Response Options. These response options are one of the most important developments in JEF’s evolution because they move the framework closer to practical crisis response. They were developed to address threats, deter malign activity and provide ways to respond quickly to crises, including threats to critical national infrastructure. Their activation after the Balticconnector incident in 2023 demonstrated that JEF can move beyond exercises and statements into operational signalling and maritime presence. At the same time, the usefulness of response options depends on speed, clarity, political thresholds and the ability to generate visible effect before uncertainty hardens into crisis.
The fourth challenge is integrating new domains and technologies. The regional security environment JEF faces is no longer limited to conventional military manoeuvre. It includes cyber operations, electronic warfare, cognitive pressure, unmanned systems, seabed infrastructure vulnerability, satellite dependency, contested data environments and the use of commercial or civilian infrastructure as part of the operating space. This requires JEF to think beyond traditional force packages. The framework will need to strengthen how members share situational awareness, protect data flows, integrate unmanned systems, coordinate cyber resilience and understand adversary influence activity across the same geography where military operations would unfold.
This is not only a technological issue. It is a command, policy and information-sharing issue. Shared situational awareness across the Baltic Sea, Danish Straits, North Sea, North Atlantic and High North requires more than sensors. It requires classification practices, legal authorities, data standards, trusted networks, joint operating procedures and agreed thresholds for action. JEF can become more valuable if it helps members build these habits before crisis conditions force improvisation. It will remain limited if new capabilities are developed nationally without sufficient attention to interoperability, information exchange and regional operational use.
The fifth challenge is maintaining readiness and interoperability across increasingly diverse force structures. JEF members operate different platforms, procurement cycles, command systems, air and naval capabilities, ground forces, reserve models and readiness arrangements. This diversity is manageable when cooperation is focused and exercised regularly. It becomes more difficult when rearmament accelerates unevenly, procurement choices diverge and national urgency pushes states towards rapid acquisitions that may not integrate well with partners. Delays in major equipment deliveries, pressure on munitions stockpiles and dependence on external supply chains make this problem more serious. Regional defence cannot be built only by buying more equipment. It must be built by ensuring that equipment, people, procedures and sustainment systems can work together.
The sixth challenge is aligning regional defence industry and procurement efforts. Europe’s defence industrial base is expanding, but fragmentation remains a persistent obstacle. National procurement priorities, industrial protection, export controls, competition between firms and different timelines can slow the creation of shared capability. JEF is not a procurement organisation, and it should not try to become one. However, it can help create a clearer regional demand signal by identifying common operational problems and encouraging members to align capability development where their security interests overlap. This is particularly relevant for maritime domain awareness, counter-unmanned systems, air defence, electronic warfare, munitions, logistics, military mobility and protection of critical infrastructure.
The seventh challenge is managing expansion without dilution. JEF’s effectiveness depends partly on its relatively small membership and geographic coherence. Expansion could bring additional capability, political weight and strategic reach, but it could also complicate decision-making and weaken the regional focus that makes the framework useful. The question is therefore not whether more members would automatically strengthen JEF, but whether any future addition would reinforce the strategic problem JEF is designed to address. Expansion must be assessed against geography, capability, political trust, interoperability and the ability to contribute to practical regional security. This issue deserves separate treatment because it goes to the heart of JEF’s identity as a focused framework rather than a general European defence club.
The final challenge is preserving trust in an environment where Europe is under pressure to fragment. States are rearming, supply chains are constrained, defence industries are competing for long-term position, and political debates over the future of European security are becoming sharper. Under these conditions, there is a risk that governments turn inward, prioritise national solutions and treat regional cooperation as an additional layer rather than a core part of deterrence. JEF’s success has rested on the opposite instinct: the recognition that national security in Northern Europe is inseparable from shared geography and shared exposure.
JEF is not a silver bullet for European defence. It cannot solve industrial shortfalls, replace NATO command arrangements, eliminate national procurement differences or guarantee political unity in every crisis. Its value lies in helping members close the gap between national action and alliance-wide mobilisation. To preserve that value, JEF must remain practical, regionally focused and operationally credible while becoming more explicit about how it supports NATO, how it responds below the threshold of armed conflict and how it helps members integrate capabilities across a contested regional operating environment.
7. Conclusion
The Joint Expeditionary Force has become one of the most effective regional defence frameworks in Europe not because it is the largest, the most heavily institutionalised or the most ambitious. Its success rests on a simpler foundation. It was built around a group of states that share a connected security environment, possess high levels of political trust and have chosen to prioritise practical cooperation over institutional expansion.
Throughout this paper, a recurring theme has emerged. JEF works because it aligns with the realities of Northern European security rather than attempting to reshape them. Its members differ in size, military capability, geography and national priorities, yet they are increasingly exposed to the same strategic pressures. The Baltic Sea, the North Atlantic and the High North form a connected operating environment where maritime security, reinforcement routes, critical infrastructure, deterrence and resilience can no longer be treated as separate issues. JEF provides a framework through which states can address these shared challenges without requiring the creation of an entirely new alliance or permanent military structure.
This helps explain why JEF has remained relevant while many multinational initiatives struggle to move beyond political declarations. The framework is built around practical requirements rather than institutional symbolism. It creates opportunities for consultation, exercises, interoperability, maritime coordination, political signalling and regional preparedness. Its credibility comes from activity rather than structure, and from the fact that participating nations repeatedly demonstrate a willingness to translate shared concerns into practical cooperation.
JEF’s importance should not be measured by whether it replaces existing institutions. NATO remains the cornerstone of collective defence for its members, and JEF’s value increases when it strengthens rather than duplicates alliance efforts. The framework is most effective when viewed as a regional layer within a wider security architecture, helping to connect national action with alliance-level deterrence and defence. In this role, it contributes not through scale alone, but through speed, familiarity, trust and regional focus.
The experience of JEF also offers a broader lesson for European defence cooperation. Effective security frameworks do not necessarily begin with new institutions, larger headquarters or more complex governance arrangements. They often begin with a shared understanding of the problem that must be solved. Geography, strategic exposure and practical military requirements create incentives for cooperation that can be more durable than institutional design alone. JEF demonstrates that when states recognise a common challenge and invest in habits of cooperation, relatively light structures can produce meaningful strategic effect.
At the same time, the framework should not be viewed as a finished model. The challenges discussed in this paper remain significant. Sustaining political attention, integrating new technologies, maintaining interoperability, aligning capability development and preserving coherence with NATO will require continued effort from all members. The strengths that have made JEF successful cannot be assumed to persist automatically. They must be reinforced through political commitment, operational activity and a continued focus on practical outcomes.
Ultimately, JEF succeeds because it is practical, regional, trusted and flexible. Its value lies not in offering a universal template for defence cooperation, but in demonstrating how like-minded states can build resilience, readiness and deterrence around a shared operating environment. In an era characterised by strategic uncertainty, contested infrastructure, compressed decision timelines and increasing pressure on regional security architectures, that lesson extends far beyond Northern Europe.
Understanding why JEF works, however, requires a deeper examination of the geography that underpins it. The framework’s effectiveness is inseparable from the strategic relationship between the Baltic Sea, the North Atlantic and the High North. These regions are often discussed separately, yet they increasingly function as parts of a single security system. Examining that relationship is essential to understanding not only JEF itself, but the wider transformation taking place across Northern European defence.
References and Suggested Reading
Official JEF Sources
Joint Expeditionary Force. About the JEF https://jefnations.org/about-the-jef/
Joint Expeditionary Force. History of the JEF https://jefnations.org/about-the-jef/history-of-the-jef/
Joint Expeditionary Force. JEF Leaders Joint Statement (October 2023) https://jefnations.org/wp-content/uploads/2023/12/20231013-jef-leaders-joint-statement.pdf
Joint Expeditionary Force. Recent JEF Activity to Protect Critical National Infrastructure https://jefnations.org/2024/01/16/recent-jef-activity/
Government Statements and Policy Documents
The Government of Sweden. The JEF Vision: Working Together as One https://www.government.se/contentassets/c7b847cc5b9f49fc8de64dd0006278f4/jef_vision.pdf
UK Ministry of Defence. Joint Expeditionary Force (JEF) – Policy Direction (July 2021) https://www.gov.uk/government/publications/joint-expeditionary-force-policy-direction-july-2021
UK Ministry of Defence. Joint Statement by Joint Expeditionary Force Ministers (November 2023) https://www.gov.uk/government/news/joint-statement-by-joint-expeditionary-force-ministers-november-2023
Government Office of Estonia. Prime Minister Kallas: Joint Expeditionary Force Ready to Respond to Protect Critical Undersea Infrastructure https://www.valitsus.ee/en/news/prime-minister-kallas-joint-expeditionary-force-ready-respond-protect-critical-undersea
Government of Sweden. Sweden to Take Part in JEF Activity to Protect Critical Infrastructure in the Baltic Sea https://www.government.se/press-releases/2023/11/sweden-to-take-part-in-jef-activity-to-protect-critical-infrastructure-in-baltic-sea/
The Danish Armed Forces. Joint Expeditionary Force 2023 Booklet https://www.forsvaret.dk/globalassets/fko—forsvaret/dokumenter/oevrige/-jef-booklet-.pdf
Parliamentary, Defence and Policy References
UK House of Commons Library. What is the Joint Expeditionary Force? (2024) https://commonslibrary.parliament.uk/research-briefings/cbp-10074/
Finnish Defence Forces. JEF Cooperation https://puolustusvoimat.fi/en/international-activities/jef-cooperation
Ministry of National Defence of Lithuania. Joint Expeditionary Force (JEF) https://kam.lt/en/faq/joint-expeditionary-forces/
Think Tank and Analytical Reading
Royal United Services Institute (RUSI). The Joint Expeditionary Force and its Contribution to European Security (2024) https://www.rusi.org/explore-our-research/publications/occasional-papers/joint-expeditionary-force-and-its-contribution-european-security
Royal United Services Institute (RUSI). Stretching the Joint Expeditionary Force: An Idea for Our Times (2023) https://www.rusi.org/explore-our-research/publications/commentary/stretching-joint-expeditionary-force-idea-our-times
Finnish Institute of International Affairs (FIIA). The Joint Expeditionary Force in Northern Europe https://www.fiia.fi/en/publication/the-joint-expeditionary-force-in-northern-europe
Center for Strategic and International Studies (CSIS). The Joint Expeditionary Force: Global Britain in Northern Europe (2022) https://www.csis.org/analysis/joint-expeditionary-force-global-britain-northern-europe
Center for Strategic and International Studies (CSIS). The Joint Expeditionary Force: From Northern Europe to Ukraine (2024) https://www.csis.org/analysis/joint-expeditionary-force-northern-europe-ukraine
International Centre for Defence and Security (ICDS). The Joint Expeditionary Force: Baltic Interests (2024) https://icds.ee/en/the-joint-expeditionary-force-baltic-interests/
Wilson Center. The UK-Led Joint Expeditionary Force’s Impact on Northern European Security (2024) https://www.wilsoncenter.org/article/uk-led-joint-expeditionary-forces-impact-northern-european-security
Additional Reading
Eva Sula. JEF, Defence Cooperation and Northern European Security https://www.linkedin.com/posts/eva-sula-02b9a73_jef-defence-nato-share-7418897607688830977-NiQ8/?utm_source=share&utm_medium=member_desktop&rcm=ACoAAACuNWMB01mVJbkCqgES16cax_p6qgUB3JQ
Eva Sula. Why JEF matters https://www.linkedin.com/posts/eva-sula-02b9a73_jef-balticsea-arcticsecurity-share-7438072442784346112-N-up/?utm_source=share&utm_medium=member_desktop&rcm=ACoAAACuNWMB01mVJbkCqgES16cax_p6qgUB3JQ
Brendan Simms. The Hour of the JEF (Centre for Geopolitics, University of Cambridge) https://www.cfg.cam.ac.uk/wp-content/uploads/2026/02/hourofJEF-1.pdf