Annual Consensus Statement: Second Track Nuclear Dialogue in Europe

Key Chapter Titles

1. National Policy, Alliance Management, and Extended Deterrence
2. Modernization and Integrated Air and Missile Defense
3. Arms Control and Non-Proliferation
4. Addressing Challenges in a Dynamic Security Environment
5. Conclusion

Document Introduction

This report is a consensus statement achieved in 2025 by the U.S.-U.K.-France Trilateral Second-Track Nuclear Dialogue project, organized by the Center for Strategic and International Studies (CSIS) in partnership with the Royal United Services Institute (RUSI) and the Fondation pour la Recherche Stratégique (FRS). Launched in 2009, this dialogue mechanism brings together senior nuclear policy experts from the United States, the United Kingdom, and France (collectively known as the P3), including former senior officials and renowned scholars and experts from the three countries. Its aim is to conduct in-depth discussions on issues such as nuclear deterrence, arms control, and non-proliferation policies, to identify areas of common concern and seek consensus, thereby enhancing trilateral cooperation in addressing complex nuclear policy challenges. This statement reflects the 2025 dialogue's assessment of a series of emerging strategic challenges facing the P3.

The report first examines policy dynamics within the P3 concerning alliance management and extended deterrence. The July 2025 "Northwood Declaration" is viewed as a historic step in U.K.-France nuclear cooperation, laying the groundwork for both nations to play a stronger role in European security. The coordination of British and French deterrence policies aims to enhance the efficiency of P3 cooperation, demonstrate the readiness of European nuclear forces to address the current security environment, while maintaining independent decision-making centers to increase adversary uncertainty, thereby strengthening European deterrence. Such policy adjustments, alongside major defense procurements such as the U.K.'s decision to acquire nuclear-capable F-35A aircraft and rejoin NATO's Dual-Capable Aircraft mission, signal that London and Paris are taking action to bolster NATO's overall nuclear deterrence. The statement emphasizes that U.K.-France cooperation aims to complement, not replace, U.S. extended nuclear deterrence in Europe. Concurrently, the United States should continue advancing the modernization of its nuclear arsenal and leverage the high degree of consensus within Congress to ensure tangible progress on the recommendations of the 2023 Strategic Posture Commission and the 2024 Defense Committee. The report notes that domestic political divisions in the U.S. may hinder necessary modernization efforts, and that the optimal resource solution for meeting current deterrence requirements relies on collective action and alliance coordination.

Regarding capability development, the report highlights the importance of modernization and integrated air and missile defense. The ongoing Russia-Ukraine war continues to underscore the transformative role of long-range precision strike capabilities and missile defense in modern conflicts. Europe's European Sky Shield Initiative and the U.S.'s Gold Dome Initiative represent significant investments in missile defense by both sides. The report argues that although Europe and the U.S. face different challenges in homeland missile defense, continued collaboration among P3 members will enhance the efficiency and effectiveness of scaling missile defense system deployments. Simultaneously, all P3 nations are advancing modernization programs for their nuclear deterrent forces, including France's deployment of the M51.3 submarine-launched ballistic missile and modernization of the ASMPA-R air-launched cruise missile, the U.K.'s return to NATO nuclear missions via the F-35A, and the U.S.'s comprehensive nuclear force modernization, including enhanced theater nuclear capabilities. These modernization efforts are crucial for ensuring sufficient extended deterrence coverage, maintaining credible independent decision-making centers, and providing the P3 with flexible escalation management options across theaters and domains.

In the realm of arms control and non-proliferation, the report notes that while the P3 remains willing to engage sincerely in arms control when conditions permit, Russia and China appear to have little interest in substantive arms control measures for the foreseeable future. Russia's violations of the New START treaty provisions and the INF Treaty indicate it does not take arms control seriously, and any proposals from it should be viewed with high skepticism. Furthermore, Russia and China show little willingness to actively cooperate with other P5 (the five permanent members of the UN Security Council) members on non-proliferation issues. Adversarial resistance to U.S. extended deterrence—a fundamental tool for preventing ally proliferation—even suggests that Russia and China may prioritize their own strategic considerations over non-proliferation to a greater extent than before.

The report concludes that the P3 is facing a dynamic and challenging security environment. Russia's continued aggression, differing perceptions of nuclear threats within NATO, the costs and collaboration challenges of large-scale missile defense, and the near-collapse of strategic arms control frameworks coupled with declining willingness for non-proliferation cooperation collectively constitute complex challenges. The upcoming Nuclear Non-Proliferation Treaty (NPT) Review Conference in April 2026 will be a focal point for these pressures. Therefore, the P3 should demonstrate unity and commitment to the treaty before and during the conference, while working to counter misinformation regarding extended deterrence and nuclear sharing, and developing a more ambitious agenda for the P5 process. In the face of adversaries' efforts to undermine P3 cooperation, divide NATO, and develop new capabilities to offset NATO advantages, continued P3 dialogue and collaboration are more critical than ever.