From Denial to Punishment: Emerging Nuclear Readiness among NATO’s Eastern Allies

Since Russia’s full-scale invasion of Ukraine, Europe’s security architecture has entered a phase of accelerated transformation in which deterrence has again become a central strategic idiom. This paper examines the emerging nuclear-relevant posture among four non-nuclear NATO allies – Poland, Finland, Romania, and Czechia – currently introducing the F-35A fighters. Building on conceptual debates in deterrence theory, particularly the shift from deterrence by denial toward deterrence by punishment (Filippidou 2020), the study argues that these states are quietly developing the political, organizational, and operational preconditions for contributing to NATO’s nuclear mission despite lacking any formal role. Deterrence by punishment, understood as credibly signaling the capability and intent to impose costs on an aggressor irrespective of battlefield outcomes, has gained renewed salience in an environment of heightened strategic uncertainty. As outlined by Mazzarr et al. (2024), contemporary deterrence requires tailored signalling, credible escalatory potential, and integration across domains and allies, cf. features increasingly enabled by the F-35’s dual-capable architecture and its role in alliance-wide integrated deterrence. Using a structured, focused comparison, this article traces documentary indicators from 2022–2025 – parliamentary debates, ministerial statements, defense reviews, and participation in exercises such as Steadfast Noon – to map whether these frontline states are moving from silence to exploration, or from exploration to preparatory steps, on nuclear-related roles. Evidence drawn from national debates and defense planning suggests converging trajectories: although none seek formal nuclear-sharing status, all four frame F-35 acquisition within a broader NATO deterrence architecture, while some (notably Poland and Finland) increasingly link modernization to potential future DCA alignment. This dynamic unfolds amid growing doubts about long-term U.S. commitment and within an emerging European imperative for greater strategic responsibility. The findings suggest that Europe’s eastern allies are quietly forming a “second ring” of deterrence, reinforcing NATO cohesion while simultaneously embedding nuclear deterrence thinking more deeply within a distinctly European strategic narrative.