Nervous Allies and Trump: NATO’s Nuclear Lesson

Key Chapter Title List

1. Balancing Strategies for Nuclear Sharing
2. Nuclear Sharing Options: Lessons Learned
3. True Sharing: Maximizing Positive Control
4. Pseudo-Sharing: The Multilateral Nuclear Force (MLF)
5. The Solution: Operational Sharing, Strategic Dependence
6. The Uncertain Future of Nuclear Sharing
7. The Case of South Korea
8. Beyond South Korea: Other Regional Considerations
9. Is Nuclear Sharing Worth It?
10. Conclusion: The Limits of Symbolic Compromise

Document Introduction

This study, authored by Richard K. Betts, was published in *The Washington Quarterly* 2025 edition. The core issue of the report is that with the potential return of former U.S. President Donald Trump to power, his questioning of and transactional attitude towards America's traditional alliance commitments have exacerbated the long-standing strategic dilemma faced by allies (particularly non-nuclear allies): on one hand, the fear of abandonment under the U.S. nuclear umbrella, meaning the U.S. might be unwilling to honor its nuclear escalation commitments during a crisis; on the other hand, the fear of entrapment, meaning being dragged by the U.S. into a nuclear conflict initiated by it that does not align with their own interests. This dilemma, prominent in the early Cold War within the NATO framework, has intensified once again under the combined effects of current geopolitical tensions (such as the Russia-Ukraine war and North Korean nuclear threats) and declining U.S. reliability.

By systematically reviewing the evolution of nuclear weapons control arrangements within NATO since the 1950s, the report provides a historical framework for assessing the potential options for current allies. The analysis covers the true sharing of the Eisenhower era, which emphasized positive control (ensuring weapons could be used quickly) while substantially relaxing regulations, to the Kennedy era's tightening of control through technical means like Permissive Action Links (PALs), and the ultimately aborted concept of the Multilateral Nuclear Force (MLF), once discussed as a political compromise. The report points out that the model NATO ultimately established and continues to this day is operational sharing, strategic dependence: the U.S. retains physical custody of nuclear weapons during peacetime and maintains veto power over their use through technical means, while allies only participate in operational planning. This arrangement is largely symbolic and does not grant allies the substantive capability to independently use nuclear weapons in a crisis.

Based on NATO's historical experience, the report delves into an analysis of South Korea, the case most likely to face the nuclear sharing choice today. Faced with North Korea's growing nuclear and missile threats and the potentially weakened security commitments from a Trump administration, there are significant divisions within South Korea (especially between the public and elites) regarding the pursuit of nuclear armament. Citing polling data, the report notes that while a majority of the South Korean public supports acquiring nuclear weapons, the elite tend to favor a more cautious approach; among various nuclear options, shared control holds a certain compromise appeal for South Korean elites compared to fully independent nuclear development or maintaining the status quo. However, the report also emphasizes that the concept of sharing itself is vague, and its strategic value depends on the actual distribution of control (the trade-off between positive and negative control). Within the framework of the U.S.-South Korea bilateral alliance, its final form may still not fundamentally resolve fears of abandonment.

The report concludes by exploring the applicability of nuclear sharing schemes in other regions (such as Japan and Europe) and assessing their overall value. The conclusion argues that, apart from the no-longer-existent Eisenhower-style true sharing, the nuclear sharing arrangements that have appeared in history are essentially symbolic compromises between complete dependence and independent nuclear possession. As long as the country providing the nuclear weapons (such as the U.S.) retains the ultimate veto power (negative control) over their use, sharing cannot substantively resolve allies' fears of abandonment nor prevent their entrapment. In the current context of Trump's impact on the alliance system and increased strategic uncertainty, the value of such symbolic arrangements is limited and may struggle to alleviate allies' deep-seated strategic anxieties. Ultimately, allies will still face the fundamental choice of whether to take the step towards independent nuclear armament.