While disrupting the European security order, Russia’s war of aggression against Ukraine has prompted an unprecedented acceleration of EU foreign, security, and defence policy developments. In this context, however, although witnessing increased EU unity and an unprecedented involvement of EU institutions, the EU’s foreign policy responses remain partly determined by the bigger states. In this regard, while the anticipation of the UK’s exit from the EU following the 2016 referendum had triggered a first acceleration in EU foreign and security policy developments –especially in defence– European responses to Russia’s war of aggression has brought the UK back into a leading role alongside France and Germany, notably through the ‘Coalition of the Willing’ for Ukraine. Revisiting the idea of a European ‘Big Three’ against the backdrop of the literature on differentiation and ad hoc coalitions in EU foreign policy, and drawing insights from three cases of initiatives before (‘Balkan Contact Group’), over (‘E3’) and after (‘Coalition of the Willing’) Brexit, the paper seeks to explain the UK’s enduring role in EU foreign policy at both the empirical and theoretical-conceptual levels.

After the signing of the 2010 Lancaster House treaties, Franco-British defence cooperation focused on resource integration and force projection. The return of state-on-state conflict in Europe and the limitations of multilateral frameworks like NATO and the EU have triggered the need for more flexible ad hoc security arrangements. From the Lancaster House 2010 agreements, which contemplated joint expeditionary operations, the mission profile has refocused on the Euro-Atlantic theatre, deterrence and territorial defence. This transition reflects the lessons of the war in Ukraine, the need for industrial scaling-up, and the ability to fight a peer-to-peer adversary.

This paper focuses on the specific case of the ‘Coalition of the Willing’ for Ukraine, discussed by both countries in November 2024 and which materialised from March 2025, as the illustration of this new paradigm. Rather than acting as an exclusive relationship, the Franco-British bilateral relationship now works as a catalyst for wider cooperation, using the unique status of both countries as the only nuclear-armed powers and leading military allies in Europe to mobilise wider groups of like-minded allies in Europe and beyond.

Based on a number of interviews with French and British officials, this paper argues that the Lancaster House 2.0 agreement signed in July 2025 ultimately aims at serving as a basis for reinforced cooperation in Europe. The CJF is designed as an open architecture where the core is bilateral but it is intended to provide the joint planning framework for a larger force that could operate in Ukraine or elsewhere, including under the NATO umbrella. Theoretically, it discusses the possibility of using ‘coalition of the willing’ as a concept in security studies in order to analyse the soft interplay between bilateralism and minilateralism.

Major crises, especially those involving the threatened or actual use of force, are commonly regarded as windows of opportunity for strategic cultural change, but whether and to what extent such change occurs depends on various factors. This is illustrated by Germany's divergent responses to the 2014 Crimean crisis and Russia's full-scale invasion of Ukraine in 2022. Drawing on longitudinal content analysis of German official documents and elite interviews conducted in Berlin, this paper traces change and continuity across key dimensions of German strategic culture between 2008 and 2025. It argues that the 2014 Crimean crisis produced remarkable continuity at the cultural level, with change largely confined to limited elite debates. By contrast, Russia's 2022 invasion triggered incremental change in strategic culture, though this process remains uneven and contested. The paper explains this divergence by highlighting the distinct nature of the two crises, the influence of norm entrepreneurs, and the institutionalised historical constraints. While it is still too early to draw conclusions about the post-2022 trajectory, the current reshaping of German strategic culture represents an emerging, though still incomplete, departure from established patterns.

Against the backdrop of Russia’s war against Ukraine, which has exposed shortages in ammunition and capabilities, bringing defence back to the heart of the European agenda and prompting a comprehensive EU rethink of armaments policy, this article examines how two leading EU military powers, France and Germany, have redefined rearmament since February 2022, and whether this process has become politicised. It assesses whether the European rearmament process has altered the way in which the French and German governments conceptualise rearmament, and whether this reconceptualization has generated political contestation within each polity. Using discursive institutionalism, the article analyses governmental discourses on rearmament and how they are received within the French and German polities, relying on a mixed-methods approach that combines quantitative and qualitative data analysis. By focusing the analysis on two key aspects of rearmament (defence spending and the military-industrial dimension), the article demonstrates that both states primarily reconceptualise Europe’s rearmament at the state level. This leads to a quiet reconceptualization in the French case, whereas Germany seems to undergo a louder reconceptualization of rearmament.