Projects / Initiatives

With the assistance of grants from the Australian Research Council (ARC) and Department of Defence, Professors Stephan Frühling (ANU) and Andrew O’Neil (Griffith University) examined the history of US nuclear weapons cooperation in the Cold War and beyond, across alliances in Europe and Asia. They used this to test realist and institutionalist approaches to explaining alliance cooperation, and examined implications for the future of US alliances and Australian defence policy.

Nuclear weapons remain central to the internal dynamics of US alliances in Europe and the Indo-Pacific. But cooperation related to them has varied significantly between allies and over time.

In NATO, the US continues to ‘share’ nuclear warheads with several of its allies for delivery by their air forces, and the alliance jointly develops nuclear policy and declaratory statements on nuclear deterrence. But while Germany made significant use of these opportunities for cooperation during the Cold War and beyond, Norway – also a frontline ally – actively limited the role of nuclear weapons in its cooperation through NATO. In contrast, in the Indo-Pacific, South Korea had essentially no insight or say in the stationing of US nuclear weapons on its territory, while Japan negotiated a set of secret understandings regarding nuclear weapons and US bases in Japan. In both countries, US nuclear weapons have been withdrawn since 1991, but unlike Australia, which never had US nuclear weapons on its territory, both Japan and South Korea both established fora for formal policy consultation and discussion on deterrence and nuclear weapons with the United States.

Based on in-depth case studies of cooperation on US nuclear weapons in Germany, Norway, Japan, South Korea and Australia, the project shows that contrary to realist theory, US allies have wielded significant influence in shaping nuclear weapons cooperation with the US in ways that reflect their own, often idiosyncratic, objectives. US allies have at times reduced, and in some cases declined, material cooperation that would have visibly linked US nuclear weapons to their own security. In general, this reflected their own assessments of the role of US nuclear weapons in allied security, which demonstrates that the value of nuclear weapons for security is not fixed, and ‘nuclear strategy’ is a negotiated and contested concept between allies. Alliances are more than mere tools of external balancing, and structured cooperation on US nuclear weapons has been a deliberate tool to promote policy convergence within them.


Professor Stephan Fruhling.jfif

Professor Stephan Frühling teaches in the Strategic and Defence Studies Centre at the Australian National University and has widely published on Australian defence policy, defence planning and strategy, nuclear weapons and NATO.

Stephan was the Fulbright Professional Fellow in Australia-US Alliance Studies at Georgetown University in Washington DC in 2017. He worked as a ‘Partner across the globe’ research fellow in the Research Division of the NATO Defense College in Rome in 2015, and was a member of the Australian Government’s External Panel of Experts on the development of the 2016 Defence White Paper.

Professor Andrew O’Neil is Acting Dean of the Graduate Research School at Griffith University. He has published widely in the broad areas of international relations and strategic studies and is currently chief investigator on projects focusing on the Australia-US alliance funded by the Australian Research Council and Australia’s Department of Defence.

Andrew is a former member of the Australian Foreign Minister’s National Consultative Committee on Security Issues and is a member of the Australian Research Council’s College of Experts.

Professor Andrew O'Neil
Andrew O'Neil

Nuclear weapons cooperation has been a crucial factor in reinforcing institutional commitment within alliances and achieving consensus on strategic priorities. It promotes alliance cohesion at times when that cohesion is potentially threatened by perceptions of differing strategic priorities among allies. Rather than being a bargain in its own right, nuclear weapons cooperation creates the basis of trust and commitment upon which allies are then able to negotiate–and strike–the necessary deals on burden-sharing and alliance strategy.

This has significant implications for the role of nuclear weapons and deterrence in US alliances today. US allies therefore need to become more embedded in, and proficient with, discussions with Washington over escalation and nuclear deterrence. To achieve closer integration and strengthen multilateral deterrence, the United States and its Indo-Pacific allies need to develop a shared understanding of escalation dynamics; maintain political unity about a shared approach to deterrence; move from consultation to joint assessment, policy and planning; conduct reviews of alliance force structure and posture and their implications for escalation; and engage in public campaigning for nuclear deterrence.

All of these are all mutually reinforcing. In combination, they would be transformative for US alliances in the Indo-Pacific, because they involve accepting a degree of heightened strategic risk that many allies have so far eschewed. Failure to agree on expectations and commitments in relation to deterrence and escalation pathways runs the risk of the US and its allies not being able to take unified action during a crisis.

Longer term, these findings also raise the question of what a greater role for nuclear weapons in US alliances in the Indo-Pacific might look like. Calls for ‘nuclear sharing’ of US warheads are rising in South Korea and Japan. Historically, forward-based nuclear weapons have helped in ‘coupling’ to US strategic forces, in the creation of inadvertent risks of escalation for potential adversaries, and in facilitating limited nuclear use options. While all of these would also be relevant for a return of US nuclear weapons to the territory of Indo-Pacific allies, the project suggests that the increased political and military integration in these alliances that could be catalysed by nuclear weapons cooperation could be even more consequential.

Book launches

Based on this research project, Professor Frühling and Professor O’Neil have published two books  –  Partners in Deterrence: US nuclear weapons and alliances in Europe and Asia, and Alliances, Nuclear Weapons and Escalation: Managing Deterrence in the 21st Century. Reviews of these books have been published in the Australian Journal of Defence and Strategic StudiesComparative Strategy, and International Affairs.


Partners in Deterrence: US nuclear weapons and alliances in Europe and Asia

Since the dawn of the atomic age, nuclear weapons have been central to the internal dynamics of US alliances in Europe and Asia. But nuclear weapons cooperation in US alliances has varied significantly over time and space. Partners in Deterrence goes beyond traditional accounts that focus on US policy regarding deterrence and reassurance, and instead places the objectives and influence of US allies at the centre of analysis. Through several case studies, Stephan Frühling (ANU Coral Bell School of Asia Pacific Affairs) and Andrew O’Neil (Griffith University) reveal that US allies have wielded major influence in shaping nuclear weapons cooperation with the US in ways that reflect their own, often idiosyncratic, objectives.

Alliances, Nuclear Weapons and Escalation: Managing Deterrence in the 21st Century

In an era of great power competition, the role of alliances in managing escalation of conflict has acquired renewed importance. Nuclear weapons remain the ultimate means for deterrence and controlling escalation, and are central to US alliances in Europe and the Indo-Pacific. However, allies themselves need to better prepare for managing escalation in an increasingly challenging geostrategic and technological environment for the US and its allies. While the challenge of great power competition is acute at both ends of Eurasia, adversary threats, geography and the institutional context of US alliances differ. This book brings together leading experts from Europe, Northeast Asia, the United States and Australia to focus on these challenges, identify commonalities and differences across regions, and pinpoint ways to collectively manage nuclear deterrence and potential escalation pathways in America’s 21st century alliances.

This book was launched by Japanese Ambassador His Excellency Yamagami Shingo. 

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Policy report and interviews

policy report analysing current policy challenges of Australia’s engagement with US nuclear deterrence was published on the website of the University of Sydney’s United States Studies Centre (USSC).

Professor Frühling was interviewed by David Trachtenberg, where he discussed the rise of China and what it means for security relationships in the Indo-Pacific region, drawing inference from his research on alliances.

Published articles

Apart from two books, Professors Frühling and O’Neil have co-published four academic articles that explored the project findings and their implications for current challenges in US alliances:


They have also written several commentary pieces over the years that draw from their extensive research.

Australian Strategic Policy Institute’s online publication The Strategist:

Lowy Institute’s The Interpreter:

Australian Institute of International Affairs’ Australian Outlook: 

Contemporary Security Policy blog: