A growing debate among strategic communities in Northern and Eastern Europe is reviving an unconventional idea: a post-NATO “Plan B” security architecture that would place the United Kingdom at the center of European defense against potential Russian aggression. While the notion remains politically sensitive and far from institutional reality, it has gained visibility among policymakers and analysts in the Nordic and Baltic region, especially amid concerns over long-term U.S. commitment to the NATO and its Article 5 collective defense guarantee.
The discussion does not suggest a formal replacement for NATO in the near term. Instead, it reflects an emerging contingency mindset: if transatlantic guarantees weaken or become politically unreliable, Northern Europe may need an alternative operational framework capable of rapid, credible deterrence against Russia.
European security planning has been under renewed strain since Russia’s full-scale invasion of Ukraine in 2022 and the subsequent recalibration of defense priorities across the continent. While NATO has expanded and strengthened its eastern posture, political uncertainty in the United States—particularly under shifting administrations and debates around burden-sharing—has revived long-standing European anxieties about overdependence on Washington.
The most sensitive concern is Article 5 of NATO, which treats an attack on one member as an attack on all. Although the principle remains formally intact, some European strategists worry that its credibility depends heavily on U.S. political will in any future crisis scenario.
Within this context, a group of Nordic and Baltic strategic thinkers has increasingly explored what they describe as a “Nordic Plus” or “Plan B” framework. The concept is not a formal alliance proposal but a conceptual map of how European states in the North could organize deterrence and defense if NATO cohesion weakens.
One of the most cited contributions to this debate comes from Finnish analysts Matti Pesu and Tomas Wallenius of the Finnish Institute of International Affairs. In a 2025 paper, they outlined a hypothetical security grouping centered on the Nordic and Baltic region, reinforced by select Western European powers.
Their model envisions Finland as the focal point of a northern defensive arc, closely integrated with Sweden, Norway, the United Kingdom, and potentially France. The logic is partly geographic and logistical: Nordic infrastructure and geography make regional reinforcement feasible in a crisis, while shared strategic concerns about Russia provide political alignment.
Pesu and Wallenius argue that these countries collectively already possess substantial military capacity, including a combined fleet of roughly 200 modern fighter aircraft. They also emphasize that wealthier Nordic states could significantly increase defense spending if required, enhancing regional deterrence.
In their framework, the United Kingdom is particularly significant. Despite its post-imperial strategic scale-down from its 19th-century peak, London remains a major military actor with global intelligence reach, expeditionary capabilities, and nuclear deterrence.
The authors describe the UK as a “serious security provider” in Northern Europe, capable of contributing across land, sea, air, and intelligence domains. France is also positioned as a potential nuclear deterrent contributor, especially if Paris chooses to extend elements of its deterrence doctrine to European partners.
The debate gained additional visibility following coverage in the British weekly The Economist, which argued that Europe should prepare not just new weapons systems, but a coherent operational structure for collective defense in the absence of guaranteed U.S. leadership.
The publication suggests that any credible “Plan B” must go beyond capability accumulation and instead focus on command architecture—how European forces would actually coordinate, deploy, and fight together in a crisis.
In this context, The Economist highlights the existing British-led Joint Expeditionary Force (JEF) as a potential nucleus for such a structure. The argument is not that JEF can replace NATO, but that it may serve as a functional fallback framework for rapid-response coordination in Northern Europe.
The Joint Expeditionary Force is a UK-led coalition formed in 2014, comprising the United Kingdom, Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Sweden, and Norway.
It was designed as a high-readiness, flexible coalition capable of rapid deployment in crises that may fall below NATO’s Article 5 threshold or require immediate regional response. Unlike NATO, it does not require unanimous consensus among all members for activation, allowing faster decision-making in emergencies.
Operationally, the JEF has no permanent standing army. Instead, participating states contribute pre-designated forces when required, enabling a modular response model. The coalition is particularly oriented toward the High North, Baltic Sea, and North Atlantic regions, where Russian naval and hybrid threats are perceived as most acute.
The JEF is headquartered at the UK’s Standing Joint Force Headquarters in Northwood, near London, which provides planning, command coordination, and secure communications infrastructure.
Proponents of the JEF-centered model argue that it offers three key advantages over ad hoc coalitions.
First, it already exists, with established interoperability between participating forces. Second, it is regionally focused on the areas most directly exposed to Russian military pressure. Third, it operates outside NATO’s unanimity constraint, potentially allowing faster operational responses.
The Economist argues that in a crisis where U.S. commitment is uncertain, a deterrent force that cannot be rapidly activated is effectively a weakened deterrent. From this perspective, JEF represents an embryonic command structure that could be expanded into a more formal European security pillar.
Despite growing attention, analysts emphasize that transforming JEF into a NATO alternative—or even a full “Plan B” backbone—faces substantial structural limitations.
The most significant constraint is that JEF does not maintain standing forces. Its reliance on voluntary national contributions means operational readiness is conditional on political alignment at the moment of crisis. In high-stakes conflict scenarios, this could delay or dilute collective response.
Second, its geographic focus is narrow. The coalition is optimized for Northern Europe and maritime security in the Baltic and Arctic regions. It is not designed for sustained operations in Southern or Central European theaters, nor for global expeditionary warfare.
Third, the force lacks heavy strategic depth. While it includes advanced air and naval assets, it does not provide the massed armored formations, logistics networks, or industrial depth required for prolonged high-intensity warfare against a peer adversary.
Fourth, major European powers such as Germany and Poland are not core members, and France participates only indirectly in the broader strategic conversation. This limits political weight and operational scale.
Finally, there are concerns about whether the United Kingdom can sustainably anchor such a system. British defense planners face budget constraints, modernization pressures, and industrial capacity limitations. Parliamentary assessments have already warned that the UK defense establishment is not fully configured for sustained collective defense operations at scale.
Underlying all “Plan B” discussions is the continued centrality of the United States to European security. Even proponents of alternative frameworks acknowledge that replacing U.S. military leadership would be extraordinarily difficult.
Historically, European defense architectures have struggled in the absence of American engagement. Analysts point to the interwar period as a cautionary example, when both Britain and France lacked sufficient economic and military strength to deter revisionist powers.
Today’s European states are wealthier and more integrated than in the 1920s, but questions remain about whether they can achieve sufficient cohesion, industrial capacity, and political unity to sustain independent deterrence.
Perhaps the most striking dimension of the debate is that even some advocates of the Nordic-centered approach acknowledge its fragility. Pesu and Wallenius reportedly suggest that if Western alignment weakens significantly, states such as Finland may eventually consider a “Plan C” involving rapprochement with Russia.
That possibility underscores the strategic uncertainty driving the entire discussion: not a rejection of NATO, but anxiety over its long-term reliability in a shifting geopolitical environment.
The emerging “Plan B” discourse does not signal the imminent replacement of NATO. Instead, it reflects a strategic insurance debate within Northern Europe—an effort to identify alternative frameworks in case the transatlantic security guarantee becomes less predictable.
Whether the UK-centered Joint Expeditionary Force evolves into a more formalized deterrence structure, or remains a supplementary coalition within NATO’s broader architecture, the conversation itself highlights a deeper transformation: Europe is increasingly thinking about its security not only in terms of alliances, but also in terms of fallback systems designed for a less certain geopolitical era.
