The current period has been dubbed the “Third Nuclear Age,” a time that combines a renewed emphasis on great power rivalry, a multipolar nuclear competition and the introduction of additional strategic assets that can destabilize deterrence relationships.^[i] In this context of multipolarity, Europe may rise as a distinct nuclear player, with specific policies, interests, priorities and forms of leverage. Historically, its views have often been shared within the “Western bloc,” coinciding with NATO deterrence and arms control policy. On occasion, European countries have been vocal in defending alternative views, for instance, in the Euromissile crisis, the Second Gulf War (2003) or following the Trump administration’s decision to withdraw from the Joint Comprehensive Plan of Action (JCPOA). The rift between U.S. interests and European priorities will probably intensify under the current conditions, following the publication of the 2026 U.S. National Defense Strategy.^[ii] This document indeed establishes clearly that Washington does not share the same security outlook as its partners, and that key threats to Europe, such as Russia, may be secondary for the United States. In addition, the harsh criticism voiced by key members of the U.S. administration against European countries, their leaders, their values, or their democratic and economic systems creates global transatlantic tensions which resonates at the strategic level as well.

European countries have strong incentives to reframe and reaffirm their positions regarding nuclear strategy more forcefully and more autonomously. This ambition will face challenges. First, “Europe” is not a clear-cut actor: NATO European allies may share perspectives on their security, but do not have an institutional framework to adopt policies. The European Union (EU) has tools and processes, in particular on nonproliferation, but is divided on the role of nuclear deterrence.^[iii] Second, Europeans may be left with little leverage to meaningfully influence the debate and push for their preferences on arms control, they may not possess the capabilities that could give them weight in negotiations; on nonproliferation, they largely depend on the United States and other major powers for the implementation of restrictive measures. These inherent limitations do not suppress the need for Europeans to revisit their role in defending and reframing the nuclear order by rethinking how nuclear deterrence can serve the security of the continent, how arms control may be used to reduce escalation risks, and how the nonproliferation regime should evolve to address current challenges.