The potential withdrawal of the United States from European security commitments has raised questions about the future of nuclear deterrence on the continent. This article explores the feasibility of France assuming the role currently played by the United States in the ‘dual-key’ nuclear sharing arrangements with European NATO members. The analysis is divided into five main sections. The article begins by outlining the strategic context in which this analysis takes place, focusing on the potential withdrawal of the United States from European security commitments and the growing emphasis on the European Union’s strategic autonomy. Against this backdrop, the article first examines France’s technical capabilities to lead a dual-key system in Europe, addressing aspects such as the number of nuclear warheads, delivery vectors, and operational compatibility with European allies. Next, it analyses the political and doctrinal implications of a French-led dual-key system, identifying which aspects of French nuclear doctrine might require revision or could create friction. The article also explores potential forums for nuclear dialogue and coordination, as well as the challenges of harmonising France’s national doctrine with a hypothetical extended framework for dual-key countries. In the third section, the article evaluates the political and security utility of a French-based dual-key system. Finally, it assesses the strategic, operational, and doctrinal implications of shifting from a US nuclear provider to a French one, highlighting both potential benefits and challenges. The findings suggest that, while a French-led dual-key system is technically feasible, significant political obstacles must be overcome for successful implementation.

The dominant view in proliferation research holds that security guarantees from nuclear patrons reduce client states’ incentives to pursue nuclear armament. Yet in South Korea, public support for indigenous nuclear capabilities remains high despite strong trust in US extended deterrence. Drawing on the “better-now-than-later” logic from preventive war theory, we argue that this support reflects public forward-looking pessimism about the security environment, shaped by perceptions of the relative decline of the US and North Korea’s advancing nuclear capabilities. Analysis of the 2023 EAI Public Opinion Poll shows that concerns about systemic power shifts and pessimism about future inter-Korean relations are significantly associated with support for nuclear armament. South Korean public assessments of US extended deterrence and North Korea’s military threat do not align with conventional alliance theory expectations that high trust in extended deterrence should reduce support for nuclear armament. These findings underscore the need for reassurance strategies that address enduring alliance credibility.

This article examines Putin’s expectations prior to Russia’s full-scale invasion of Ukraine and seeks to answer the following question: Why did Russia invade Ukraine regardless of the West’s threats of severe economic penalties raising the cost of an attack? I argue that the confidence in Vladimir Putin to invade Ukraine, despite his awareness that the stakes could go well beyond the borders of Ukraine and increase the cost of war for the Kremlin, was based on Putin’s calculations that the West would be reluctant to change or substantially displace established rich-get-richer economic structures and would not apply high costs on the Kremlin for military aggression against Ukraine in case of a successful blitzkrieg campaign. By utilizing an extended deterrence game analysis, the article demonstrates how Russia, Ukraine, and the West interacted in decision-making, taking into account the reactions and choices of the other players, and adds to the current body of knowledge by introducing an expanded approach to deterrence strategy based on economic interdependence and the scale of the anticipated conflict.