Recasting the JEF for a harder European future
The Memorandum | No. 23.2025
Calls for ‘more Europe’ in defence are not new. Neither are concerns about NATO’s political drift following the reelection of Donald Trump as President of the US or the EU’s continued operational hesitance and action-light rhetoric.
Europe has no shortage of defence structures. The North Atlantic Treaty Organisation (NATO) remains central, the European Union (EU) is making efforts and national investments are increasing. Yet, the problem is not a lack of frameworks, treaties or coalitions, it is the lack of timely, cohesive and scalable action when it matters. The Joint Expeditionary Force (JEF), comprising ten northern European nations led by the United Kingdom (UK), has quietly demonstrated how cohesive, like-minded countries can react swiftly, exercise regularly and deter credibly. However, its current format – agile but purely ad hoc – limits its potential.
Calls for ‘more Europe’ in defence are not new. Neither are concerns about NATO’s political drift following the reelection of Donald Trump as President of the United States (US) or the EU’s continued operational hesitance and action-light rhetoric. Rather than repeat these well-worn arguments, a shift can instead be proposed: formalise and expand the JEF now, not to replace NATO or duplicate the EU, but to incubate the kind of rapid, European-led response capability which the next decade will likely demand.
What makes the JEF work
The JEF’s utility comes from its speed, cohesion and clarity of purpose. It operates outside EU and NATO structures, but is interoperable with both. Decisions are opt-in; no member can block others from acting. Its structure avoids bureaucracy; its members train together, share worldviews and have proven themselves deployable in air, land and maritime domains. From Baltic patrols to exercises such as JOINT PROTECTOR, the JEF has already built habits of readiness and trust.
Its scale, however, remains modest. It includes Britain, the five Nordic countries, the three Baltic nations and the Netherlands. These are capable states, but limited in mass. The JEF was not built to defend Europe as a whole. Nor was it built for sustained operations far beyond its northern flank. Yet, in the emerging European security environment, the demand for fast, self-starting coalitions is only increasing.
A force which can act while others wait
The JEF’s opt-in model fills a strategic gap. NATO can be delayed by political friction or divergent threat perceptions – both issues which seem to be becoming increasingly frequent. At the same time, the EU’s defence tools remain underdeveloped and slow to mobilise. Both still matter deeply, but neither can guarantee substantial gait.
The JEF has already demonstrated how to respond quickly to hybrid threats. Following suspected sabotage of undersea infrastructure, its members moved within days to step up maritime surveillance and prepare joint responses. These are the kinds of fast, credible actions which shape adversary behaviour. And they are precisely the actions most vulnerable to alliance gridlock.
A larger, more formalised JEF, anchored in today’s coalition but expanded to include key European powers, would build on this template. It would not require unanimity. It would not wait for consensus. It would act when and where it can, reinforcing deterrence through visible readiness.
A light but tighter framework
The challenge is to enhance the JEF without turning it into what it is not. There is no need for a sprawling permanent bureaucracy. Instead, three changes would suffice:
First, formalise the political structure. The JEF has already begun holding annual summits. These should be made permanent and revolving, bringing together leaders and defence ministers to set strategic direction. This regular high-level engagement would strengthen cohesion, signal intent and institutionalise commitment.
Second, scale the command structure. The UK’s Standing Joint Force Headquarters has served well, but a more multinational staff, with rotating senior posts and a larger planning cell, would allow the JEF to coordinate larger operations. This can remain lean, but should be ready to lead, not just exercise.
Third, develop modular rapid response packages. Pre-agreed deployments – whether maritime, air or ground-based – should be assigned to specific scenarios. These could include undersea sabotage, cyberattacks or territorial incursions below the threshold of full-scale peer conflict, while wasting no time in planning for the unfathomable. Political pre-authorisation among core members could reduce delays and ensure the JEF acts within hours or days, not weeks.
Broadening the membership
Importantly, this is not a rejection of NATO. The JEF should remain interoperable with the alliance, feeding into its plans and bolstering its forward presence.
The case for expansion is compelling and necessary. Germany brings industrial scale and Baltic reach. France offers additional nuclear weight and a further Mediterranean presence. Poland contributes frontline urgency and military depth. Italy and Spain broaden geography and expeditionary options. These additions of immensely capable and like-minded nations would not dilute the JEF’s identity; they would empower it. Provided new members commit to its principles – opt-in action, rapid readiness and shared responsibility – the coalition would grow stronger, not slower. For those hesitant to commit fully, an observer or partner tier could ease the transition. Additionally, the force should be open to guest contributors who wish to subscribe to actions once underway.
Importantly, this is not a rejection of NATO. The JEF should remain interoperable with the alliance, feeding into its plans and bolstering its forward presence. Nor is it a rival to EU defence initiatives, which can benefit from JEF-developed practices and plug in where appropriate.
Rather, it is a hedge: a means of ensuring Europe can act while others prepare to. In an age of sub-threshold threats, uncertain American leadership and contested domains, such a hedge is no longer a luxury.
A future worth shaping
By 2030, it is not unthinkable that the JEF could become Europe’s most credible rapid response force. Not a standing army, but a standing and adaptable commitment – ready to scale, prepared to act. It would fill the void between national reaction and alliance consensus, able to move first and integrate later.
This is a uniquely British opportunity. The UK has led the JEF well. But leadership now requires vision and burden-sharing: expanding the coalition, anchoring its legitimacy and shaping it as Europe’s next-generation security instrument. This would not only reinforce Britain’s role in European defence, it would show that when institutions stall, coalitions of willing participants can still deliver in an ever-more fragmented world.
Now is the moment to act. Europe will not be more secure by default. It will become more secure only because willing nations choose to make it so. The JEF has already shown what is possible. The task ahead is to turn that possibility into permanence.
Samuel Harris is a recent graduate from the Department for War Studies, King’s College London, with a Master of Arts in International Relations. A former senior parliamentary staffer, he now writes independently on defence and strategic affairs, with a particular focus on British maritime strategy and air power.
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Very interesting. I've long thought we need to be doubling down on the JEF. I was a bit surprised you didn't mention getting Ukraine in the JEF. It would life Ukraine out of a dangerous grey zone. It will never be safe until it's part of a structured organisation or alliance where it be safe from what will certainly be a third wave of Russian aggression even if a "peace" is reached soon. Ukraine rightly distrusts paper guarantees.
This is a very interesting article Samuel and I learn't something about the JEF that I didn't know, how well coordinated it has been. I think this is something thay the UK and others need to build on. I think it's very important that members share a similar world view and common values.