JOINT EXPEDITIONARY FORCE IN EUROPEAN SECURITY SYSTEM: DEVELOPMENT PROSPECTS AND SIGNIFICANCE FOR UKRAINE
Mykhailo Samus
Director of the New Geopolitics Research Network
Summary
One of the main problems in shaping a new model of the European security system is the lack of a clear understanding of approaches to creating the military component for ensuring the joint defense capabilities of European countries. Against this background, the Joint Expeditionary Force (JEF) can be regarded as one of the multinational military-political mechanisms in Europe that is most prepared for practical application.
The shift in the American approach to Euro-Atlantic security, reflected in the rhetoric and actions of the current U.S. administration, as well as in Washington’s strategic documents, and reinforced by a new regime for distributing the defense burden within NATO, is compelling European states to move away from a logic of supplementing American power toward a model of independently ensuring their own response to challenges and risks in the security and defense sphere. In this situation, the JEF is of particular interest not only as a high-readiness coalition, but as an already existing institutional, staff, and military instrument that can be developed toward transformation – from a regional military grouping with a broad, yet still limited, functional scope into a genuine military core of the new European security and defense system.
European Security after Transformation of U.S. Administration Policy
The current discussion on a new European security system can no longer be reduced merely to countering individual threats, including the potential threat of Russian aggression against European countries. At present, Europe’s security and defense system is part of a broader process of Europe’s emergence as an independent geopolitical, economic, and military-political actor on the world stage. The catalyst for this process has undoubtedly been the change in the role of the United States in the Euro-Atlantic area. The 2025 National Security Strategy of the United States formulates this change unambiguously: the era of the United States “propping up the entire world order” is declared over; allies must assume primary responsibility for their own regions, while Washington sees itself as the “convener and supporter” of a burden-sharing network rather than the indispensable bearer of the primary defense burden. This logic was also institutionally reinforced within NATO: The Hague Summit Declaration of 2025 enshrined the allies’ commitment to raise aggregate defense and security spending to 5% of gross domestic product (GDP) by 2035, of which at least 3.5% is to be directed toward core defense requirements and the fulfillment of NATO’s capability targets.
For Europe, this means the end of a long historical period during which its security architecture could remain politically contradictory, industrially fragmented, and militarily dependent on the United States as the center of the Euro-Atlantic security space. The EU White Paper “Readiness 2030” states that Europe needs urgent rearmament, the coordination of defense investments, the rebuilding of its defense-industrial base, and the incorporation of lessons learned from modern warfare. Another particularly telling point in the document is that supporting Ukraine is identified as the most urgent task of European defense, since it is Ukraine that stands on the front line of defending shared security. For the first time, this document treats Ukraine as a central element of European military-strategic and defense-industrial planning. At the same time, the White Paper 2030 still leaves this thesis more at the level of a slogan and a political aspiration than a practical line of action, since it does not define roadmaps for its implementation. Overall, the transition from rhetoric and the announcement of new projects, which have often gone unimplemented, to practical steps aimed at building joint European defense capabilities with the mandatory involvement of Ukraine remains the main challenge for European policymakers, a significant proportion of whom still do not regard the creation of an independent European system as an urgent task for Europe.
The current strengthening of European security is taking place primarily in the regulatory-financial and industrial dimensions. The European Union has launched the European Defence Industry Programme (EDIP) as a grant support program worth €1.5 billion for 2025–2027, of which €300 million from this package has been earmarked for a separate Ukraine Support Instrument. All of this means that Europe’s new security architecture is already taking shape as a system of resources, production, innovation, and long-term support. However, this process has not yet created a compact military core with its own operational tempo, a stable command structure, and the ability to be rapidly deployed in crisis situations and to counter military threats.
It is precisely in this respect that the main European deficit becomes apparent. The EU can create programs, financial incentives, legal regimes for cooperation, and joint procurement mechanisms. However, European policymakers have still not moved to practical steps toward creating joint military capabilities, hoping that NATO will remain the principal guarantor of collective defense in the Euro-Atlantic space. The vacuum that currently exists between European efforts to build joint capabilities in the defense industry and the uncertain prospects for the employment of NATO’s military structure calls for the creation of a purely European military structure – one less cumbersome than NATO, yet with a clear political status, defined functions, tasks, and resource provision. It is precisely for this reason that the JEF is of particular interest: it does not replace either the EU or NATO, but fills the niche in which a rapid multinational response to crisis is meant to emerge, especially in the northern and Baltic directions, with the prospect of expanding both its composition and structure and its functions and geographic scope of application.
JEF: Development, Composition, and Political Meaning of Format
The concept of Joint Expeditionary Force was initiated by the United Kingdom in 2012. After the 2014 NATO Summit in Wales, seven states – Denmark, Estonia, Latvia, Lithuania, the Netherlands, Norway, and the United Kingdom – signed the Foundation Memorandum of Understanding. In 2015, the JEF reached initial operating capability; in 2017, Finland and Sweden joined it; in 2018, the signing of the Comprehensive Memorandum of Understanding completed the institutional formation of the mechanism; in 2021, Iceland became a member of the format. Today, the JEF unites ten states, all of which are members of NATO.
The official description of the JEF defines it as a coalition of high-readiness forces capable of rapid response to crises (including those of a hybrid nature), of integration into larger-scale operations led by NATO, the UN, or other coalitions, and of conducting a full spectrum of operations across various domains. Geographically, the priority area of interest for the JEF is the Arctic, the North Atlantic, and the Baltic region. In this sense, the JEF is a territorially and functionally defined mechanism, embedded within a specific regional threat logic.
The JEF does not maintain a standing force structure. Formally, the JEF comprises approximately 10,000 service members. However, this figure should not be understood as a permanently deployed or formally established multinational grouping. The JEF forms specific force configurations from the national contributions of member states, depending on the task, theater, and political decision.
The practice of recent years confirms this modular logic. In 2024, during the exercise JOINT PROTECTOR 24 in Liepāja, more than 300 personnel from staff and support elements from ten countries were deployed, while part of the personnel remained at Northwood as part of the British Permanent Joint Headquarters (PJHQ). In 2025, the TARASSIS exercise, which the JEF described as its most ambitious “live” event since its creation, involved thousands of service members, naval and air personnel, as well as dozens of ships and aircraft in the North Atlantic, Scandinavia, and the Baltic region.
Command, Staff Architecture, and Employment Logic of JEF
The lead nation of the JEF is the United Kingdom. It is the UK that determines the structure and composition of the operational headquarters and command for specific operations. At the same time, the JEF is not a model in which other participants “hand over” their forces to the United Kingdom. National contingents always remain under the full command of their national governments and respective military structures, and participants delegate only the appropriate level of authority to the operational commander for a specific mission. It lowers the political threshold for participation, since it does not call into question states’ sovereignty over their own forces, while at the same time ensuring sufficient unity of command for joint action.
The Standing Joint Force Headquarters (SJFHQ) has been designated by the United Kingdom as the standing operational headquarters of the JEF. By its structure, the SJFHQ is joint, multinational, and interagency. It provides operational liaison and reconnaissance teams ready for deployment at immediate notice, a separate staff element ready to deploy within 24 hours, and a joint logistics staff.
As a component of the United Kingdom’s Integrated Warfare Centre, the JEF Secretariat is responsible for the day-to-day management and administration of the Joint Expeditionary Force’s activities, as well as for coordinating activities and information exchange between all structures of the lead nation and the JEF member states.
Another important feature of the JEF is its mechanism for political decision-making. Unlike many multilateral formats, the JEF uses a mechanism that does not require the consensus of all participants in order to conduct activities and deploy forces. Following consultations, Britain, as the lead nation, can organize JEF activity involving one or several member states; at the same time, none of them is automatically obliged to provide forces for every case.
The JEF’s operational model is built around two categories of instruments: JEF Integration Options and JEF Response Options. The former are responsible for ongoing integration, interoperability, the demonstration of unity, and the build-up of presence in peacetime; the latter are responsible for pre-planned crisis response options. The JEF’s operational models are designed to operate across the entire continuum from competition to conflict, strengthening multinational capabilities, protecting allies, deterring aggression, and complementing NATO.
It is precisely for this reason that the JEF is regarded as a response instrument below the Article 5 threshold. The JEF Leaders’ Statement of March 26, 2026 notes that member states intend to act quickly and flexibly, in close coordination with NATO, in crisis situations, particularly in response to security threats that fall below the Article 5 threshold. The same document describes the JEF as a bridge between national actions and NATO operations, as well as a mechanism for responding to crisis processes up to and including the phase of military conflict.
After 2022, the JEF moved from the phase of conceptual preparation to the stage of genuine functional deployment. In January 2025, the JEF activated Operation NORDIC WARDEN – a JEF Response Option – under which member states monitored shipping and threats to critical undersea infrastructure in the North Sea and the Baltic Sea, deterred potentially hostile actions, protected communication lines, and supported NATO’s Operation Baltic Sentry.
The JEF’s annual JOINT PROTECTOR exercises perform a different, but no less important, function. In 2024, they were aimed at testing the JEF’s ability to act at an early stage and respond rapidly before the development of a full-blown crisis. The scenario involved the simultaneous planning and conduct of several JEF Response Options, which could either support NATO’s combat capabilities or de-escalate the situation before the onset of open conflict. The JEF became a platform not only for multinational planning, but also for the exchange of real lessons from modern warfare.
In turn, the GLOBAL GUARDIAN and TARASSIS exercises show that the JEF is increasingly confidently moving to a multi-domain level. In GLOBAL GUARDIAN, JEF HQ acted as a coordinating body among the national air forces of several European countries in interaction with the United States and NATO; at the same time, the aircraft themselves were not under the control of the Alliance, with the JEF serving precisely as a convenient coordination hub for multilateral activity. The TARASSIS exercise, held in the autumn of 2025, became the JEF’s most ambitious activity involving troops since its creation. Being a truly multinational and multi-domain exercise, TARASSIS encompassed activities in the land, maritime, air, space, and cyber domains.
JEF as Potential Foundation for Unified Military Component of Europe
The potential for using the JEF as a foundation for creating a military component for a unified European security and defense system rests on several key institutional properties of this structure. First, the JEF has a clearly defined primary theater of operations, which can be expanded if necessary. The JEF leadership defines the Baltic region, the Arctic, and the North Atlantic as an interconnected geostrategic zone of primary shared interest. Without such a shared theater, it is impossible either to create a serious planning system, or to build up logistics, or to establish a coherent doctrinal culture. Second, the JEF includes states with a high level of political and military affinity. However, more important in this respect is the principle of flexibility when it comes to involving particular countries, with their respective components, in specific operations. That is, if the JEF format were to be expanded across the whole of Europe, countries with differing threat assessments or differing levels of readiness to participate in various operations could adapt to the specific challenges and requirements of the relevant operations. Third, the JEF already has a functioning staff mechanism, procedures, and a practice of regular political and military decision-making.
In effect, with NATO doctrine as its basis, the JEF provides a “transmission mechanism” between European states and NATO, making it possible to respond to problems regionally and to react faster than within the Alliance, without the need for lengthy decision-making procedures. The UK Strategic Defence Review 2025 discusses the advisability of developing the JEF as a capable and resolute coalition, intended to enhance NATO’s deterrence capabilities in Northern Europe and the Arctic, and to improve collective approaches to capability development.
The current discussion on the future of the JEF already goes beyond the simple expansion of exercises. The JEF Leaders’ Joint Statement of March 26, 2026 outlines several directions for further development: strengthening coordination across the entire JEF area, harmonization with NATO’s planning process, expanding contributions to enhanced vigilance activities, ensuring that JEF Response Options remain aligned with real security threats, strengthening the JEF’s role in peacetime deterrence, and deepening efforts to counter hybrid influences and the Russian “shadow fleet”.
It is important that one of the leading directions of JEF development is the maritime domain. In a speech by the First Sea Lord of the United Kingdom on April 29, 2026 , the JEF was placed at the foundation of the concept for a new Partnership of Northern Navies (PNN) – a multinational naval force for the defense of Northwestern Europe and the High North. The proposed model envisages that such a force should train together, prepare for war together, have real combat plans and genuine integration. The ultimate goal is formulated even more explicitly: the creation of a group of allied fleets, ensuring joint training in the format of Fleet Operational Standards and Training (FOST), based on British doctrinal and integration standards and command from the UK Maritime Operations Centre. If this concept is implemented, the JEF will reach a qualitatively new level – from a high-readiness coalition to a prototype of an integrated Northern allied force in the maritime domain.
Prospects for Integration of Ukraine into JEF
For Ukraine, the JEF is important above all because it is, perhaps, the first European security mechanism that has begun to institutionally embed Ukrainian combat experience into its own evolution. In November 2025, an enhanced partnership between the JEF and Ukraine was announced. The British government emphasized at the time that this partnership would not only strengthen support for Ukraine, but would also give JEF countries the opportunity to study lessons directly from the battlefield. In other words, Ukrainian experience is conceived from the outset as a component needed by the Northern European allies themselves to rethink their own doctrines. It is also telling that in 2026 the new cycle of JEF LION exercises was conceived from the outset in close coordination with Ukraine. The JEF leaders confirmed that Ukrainian units would take an active part in JEF LION, and also agreed to expand the exchange of tactical and operational experience from modern warfare, including the latest doctrinal approaches and technological innovations, through the further integration of Ukraine into broader JEF activity.
In strategic terms, the significance of this process extends beyond the JEF itself. If the EU is currently creating financial and industrial instruments for Ukraine’s integration, and NATO retains the role of the principal guarantor of collective defense, then the JEF could become a transitional, but decisive, level at which Ukraine is integrated into the new European military order as a bearer of real experience of modern warfare. It is about the possibility of influencing doctrine, planning, multi-domain deployment, models for protecting critical infrastructure, the organization of actions below the threshold of a major war, and the mechanics of a rapid transition from crisis to conflict. It is precisely in these areas that Ukrainian experience is unique for contemporary Europe, and the JEF is the most suitable environment for its operational absorption and institutionalization.
Forecasts and Prospects for Development of JEF as Core of Future Unified European Military Component with Participation of Ukraine
Based on the current development of the global situation, as well as the trend of transformation of the Euro-Atlantic space, it is most likely that in the medium term the JEF will develop in the direction of a gradual transformation from a high-readiness coalition of Northern European states into one of the central military-political mechanisms of the new European security system. First, European states are increasingly clearly recognizing the need to independently ensure their own security amid the declining predictability of the U.S. role in the Euro-Atlantic space. Second, none of the existing EU instruments ensures a rapid transition from political decision to actual military response. Third, it is precisely the JEF that already has what most other European initiatives lack: a proven staff mechanism, political flexibility, procedural readiness for deployment, a multi-domain format of action, and a track record of application in crisis conditions.
In the medium term, a further shift in the JEF from the logic of regional response to the logic of permanent deterrence should also be expected. Whereas at the initial stage the JEF was viewed primarily as an instrument for local response in the North Atlantic, the Baltic region, and the Arctic, the discussion now concerns the formation of a permanently operating mechanism of collective military capabilities, capable of functioning not only at the moment of escalation, but also in peacetime as an element of strategic pressure on the adversary. Indeed, the development of JEF Response Options, the shift toward continuous monitoring of threats to critical infrastructure, and the orientation toward actions below the Article 5 threshold indicate that the JEF is gradually moving into a niche that could be defined as a European instrument of forward deterrence and early military response.
A likely direction for the evolution of the JEF is the deepening of its staff and command integration. At the first stage, this will not mean the creation of a supranational general staff in the classical sense, but rather the expansion of the standing capabilities of SJFHQ, the strengthening of the role of the JEF Secretariat, the improvement of operational planning mechanisms, and the further convergence of command, logistics, communications, intelligence, and situational awareness procedures. Going forward, it is precisely this system that could become the basis for a broader European military superstructure, within which the JEF would perform the function of a hub for rapid multinational command.
A separate, and possibly the most important, direction for the development of the JEF could be the maritime component. If the concept of creating a Northern navies partnership system based on the JEF is implemented, this would mean the emergence of, in effect, the first integrated multinational European force segment of a new type. Its significance would extend far beyond maritime security. It would become a testing ground for working out the interchangeability of platforms, joint logistics, unified combat training standards, digital interoperability, and collective planning.
No less important appears to be the prospect of the functional expansion of the JEF beyond the purely Northern theater. Formally, its priority geographic zone will remain within the North Atlantic, the Arctic, and the Baltic region. However, in accordance with the logic of the development of European security, the JEF will inevitably extend into a broader perimeter, primarily through strengthening ties with the Black Sea region. This does not necessarily mean an immediate expansion of membership, but primarily institutional interaction with states for which the Black Sea theater is critical from the standpoint of deterring Russia. It is here that the Ukrainian factor becomes decisive. Without Ukraine, any attempt to build a European system for deterring Russia would be artificial and incomplete.
Ukraine is the only European state that today possesses full practical experience of waging a major modern war against Russia across all domains – on land, at sea, in the air, in cyberspace, in the field of unmanned and robotic systems, in air defense, deep strikes, combat logistics, and the protection of critical infrastructure. Ukraine is capable of significantly influencing the very philosophy of the JEF’s employment, shifting it from the level of classical expeditionary thinking to the logic of next-generation multi-domain defense.
In practical terms, this would mean the gradual inclusion of Ukraine in several basic tracks of JEF development. The first track is operational-tactical. This concerns the regular participation of Ukrainian units in exercises, staff training, and crisis response scenarios. The second track is doctrinal-conceptual. Here, Ukraine could become a source of systematized lessons for the JEF in waging war under conditions of mass drone use, actions during hybrid scenarios, the protection of undersea and land-based critical infrastructure, as well as the integration of combat experience into the training cycle. The third track is defense-industrial. Within the framework of strengthening the European defense-industrial base, Ukraine’s participation in joint production, the adaptation of weapons systems, and the development of missile, unmanned, naval, and counter-air systems could become a practical basis for the integration of the JEF with the new European defense industry.
However, it should be considered that the evolution of the JEF to the level of the core of a future unified European military component will not be automatic. It will be constrained by at least three limitations. The first limitation is political. Far from all European states are yet ready to think in terms of the actual creation of a separate European center of military power. The second limitation is institutional. Time is needed for the JEF to converge with NATO’s broader mechanisms and, possibly, with certain EU defense instruments, without the JEF itself losing its flexibility. The third limitation is resource related. The transition from a high-readiness coalition to a genuinely integrated military nucleus will require significant investments in command structures, communication networks, logistics hubs, joint stockpiles, digital infrastructure, intelligence, maritime surveillance, air defense and missile defense, and operational support systems. Therefore, the most realistic scenario appears to be not a revolutionary one, but a gradual one: the JEF first establishes itself as the primary Northern instrument of deterrence, then expands its functions, the geography of its partnerships, and its level of integration, and subsequently becomes the foundation of a broader European military construct.
Conclusions
The analysis conducted provides grounds to assert that the JEF extends beyond the purely regional format of a Northern European high-readiness coalition. Its evolution from a rapid-response mechanism to an instrument of permanent deterrence, multi-domain planning, and the coordination of actions below the threshold of a large-scale war indicates the formation in Europe of a new type of military-political organization. It is the JEF that has now come closest to the form that could, in the future, be regarded as the initial military core of the new European security and defense system.
For Ukraine, this opens a window of strategic opportunities. Unlike many other European formats, the JEF has already begun to institutionally embed Ukrainian combat experience into its own development. Considering this, Ukraine should regard itself not as an external partner of European security, but as one of its future co-creators. The key point is that, without Ukraine, the new European system for deterring Russia will be incomplete, both conceptually and practically. It is Ukraine that currently possesses unique experience of modern large-scale war, multi-domain employment of forces, the integration of unmanned systems, adaptive air defense, the protection of critical infrastructure, and the operational transformation of doctrines under the pressure of real combat.
In this context, Ukraine’s foreign policy task lies not only in maintaining partnerships with individual JEF member states, but in the gradual consolidation of Ukrainian presence within the very process of the JEF’s institutional expansion. If the EU is currently moving primarily along the path of financial and industrial cooperation with Ukraine, while NATO retains the role of the overall military-political umbrella, then it is the JEF that could become that intermediate, yet decisive, level at which Ukraine is able to secure a place within the future European military framework even before the end of the war. It follows from this that, for Ukraine, the JEF should be not merely another format of engagement, but one of the priority directions of its long-term diplomatic, military, and defense-industrial strategy.
The publication is prepared under the project “Strengthening the Analytical Capabilities of the Foreign Policy Decision-Making with the Civil Society” of the Centre for International Security with the support of the Konrad-Adenauer-Stiftung Ukraine.
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