China, explained.
What happens if the United States decides it can no longer provide a nuclear umbrella for the Indo-Pacific? (Getty Images)
With Washington’s Cold War deterrence logic no longer adequate, the region’s states are seeking alternatives.
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America’s nuclear umbrella is fraying in the Indo-PacificAmerica’s nuclear umbrella is fraying in the Indo-Pacific
The Indo-Pacific is undergoing nuclear awakening. For a region long dependent on American security guarantees, countries are now contemplating alternatives like nuclear-sharing agreements or even developing their own nuclear capabilities – something that was once considered taboo.
The Indo-Pacific already hosts five nuclear powers – the United States, China, India, Pakistan, and North Korea – with external nuclear powers such as Russia also strategically engaged in the region. Each possesses distinct doctrines, force structures, and strategic goals, resulting in overlapping deterrence dynamics. The proliferation of nuclear capabilities challenges traditional extended deterrence frameworks, which were designed for predictable rivalries and Mutually Assured Destruction (MAD). As the nuclear landscape becomes more complex, Indo-Pacific states operate in an environment where multiple nuclear relationships influence strategic stability.
Once considered peripheral, the Indo-Pacific now occupies a central role in global strategic competition.
Washington’s current nuclear strategy has not fully addressed the magnitude of this shift. As nuclear powers update their arsenals and the norms maintaining the system weaken, the key question is whether US-led Extended Nuclear Deterrence (END) remains effective. Once considered peripheral, the Indo-Pacific now occupies a central role in global strategic competition, hosting some of the world’s fastest-growing economies, major shipping routes, and vital trade hubs. Despite these changes, Washington maintains a minimalist stance on END engagement, even as the region lacks a formal nuclear framework.
If US security guarantees are not maintained and Indo-Pacific allies become hesitant to remain under the US nuclear umbrella, traditional END strategies could result in a strategic mismatch. States might adopt more radical security measures that offer greater independence and directly address their concerns about sovereignty. The following scenarios illustrate potential pathways by which END developments in the Indo-Pacific might unfold and how doubts among allies could eventually lead to a fundamental shift in the regional nuclear order. While these scenarios are hypothetical and consider the more extreme possibilities of current nuclear trends, neglecting them does not mean they are unlikely. It may be that the current status quo continues, with incremental changes such as increased conventional deterrence, missile defence, and nuclear consultation forums. However, we cannot assume that the current course will automatically stabilise. It is therefore wise to consider what outcomes might emerge.
In this scenario, the United States demands that Indo-Pacific nations join its existing END structure or nuclear umbrella, extending beyond allies such as Australia, Japan, and South Korea to include like-minded states or regional partners. Traditional allies might be compelled to host nuclear weapons under US sovereign control, helping to limit proliferation in the region.
Or the United States might decide it can no longer take on the full cost of providing a nuclear umbrella to the Indo-Pacific region, but still wishes to expand its current END framework. Washington could therefore advocate for controlled proliferation in the Indo-Pacific. This would likely involve the United States and possibly other allied nuclear powers negotiating the possibility of sharing nuclear technology with key regional allies and partners, such as Australia and Japan, to develop their nuclear capabilities. When these nations deploy such capabilities, either by receiving nuclear weapons or gaining the ability to build them, they will shift the regional power balance.
In response, it is likely that China and Russia would supply nuclear capabilities to friendly states, further increasing proliferation risks. This could lead to a patchwork of nuclear-armed states or a disparity between those with nuclear technology and those without or seeking it.
China's DongFeng-5C nuclear missiles, which have a global strike range, pass through Tiananmen Square on 3 September 2025 (Sheng Jiapeng/China News Service/VCG via Getty Images)
The United States could ultimately lose control over proliferation management in the region. Allowing its allies and like-minded states to acquire and use nuclear weapons for sovereign purposes not only means that control over the launch trigger is no longer in US hands but also raises the risk that, if political instability occurs in any of those states, nuclear technology could spread beyond their borders.
Ultimately, extending and broadening the current US-led END framework might render it ineffective if a patchwork of nuclear-armed states emerges in the Indo-Pacific, potentially forming their own alliance networks beyond centralised US control. Alternatively, though less likely, controlled proliferation could lead to a regional balance – as some realists suggest – where increased nuclear capabilities might impose greater responsibilities and frameworks, and where MAD and counterstrike doctrines could stabilise existing flashpoints.
At the other end of the spectrum, the United States could withdraw the nuclear umbrella from the Indo-Pacific. In this scenario, US allies would seek to build indigenous capabilities given the lack of security guarantees. Japan and South Korea would likely lead this effort, given their proximity to major adversaries and their latent nuclear capabilities. Australia would follow, possibly by obtaining technology from European allies, Japan, and South Korea, and Taiwan would build nuclear capabilities even if only in a defensive posture.
The changed nuclear posture of these states could in turn prompt other non-aligned nations involved in US–China competition, such as Singapore, Thailand, Vietnam, or Indonesia, to develop their own nuclear arsenals. But whether this more crowded nuclear environment would result in mutual deterrence and reduce escalation risks, or instead increase the possibility of miscalculation, is hard to foresee. There is a high probability that tactical nuclear weapons would be used if a conflict arose, particularly in the maritime domain.
Less plausibly, US withdrawal might result in the expansion of the non-proliferation regime.
It is also likely that such a shift would weaken the non-nuclear consensus in Southeast Asia and the Pacific and diminish conflict de-escalation efforts, such as those through ASEAN. Moreover, due to costs and proliferation risks, opposition at home and internal instability could rise both in states capable of producing nuclear arms and those that cannot. This situation might provide opportunities for non-state actors to steal nuclear materials, either through failed weapons projects or corruption fuelled by rising costs.
Alternatively, another nuclear power might step in to fill the gap and replace the current END framework, especially if states in the region see the United States as a potential nuclear threat amid increased US–China rivalry. This could lead to an existing outsider, such as India, or emerging powers like Japan or South Korea, acting as the key nuclear stabiliser.
Less plausibly, US withdrawal might result in the expansion of the non-proliferation regime. A nuclear-free regional alliance could emerge, bolstering a new rules-based order that excludes nuclear-armed states. This might serve as a non-aligned movement amid US–China competition, restricting the engagement of both powers in the region.
A third scenario is the emergence of an alternative nuclear umbrella in the Indo-Pacific. Growing anxieties about the credibility of US-led END could lead some regional states to pursue partial strategic accommodation with Beijing, avoiding explicit alignment with China while reducing reliance on US deterrence. For Indo-Pacific states that are unwilling to accept protection under the US nuclear umbrella, issuing clear statements that they do not seek such protection could help reduce their risk of becoming targets in a war between the two superpowers. For many Southeast Asian nations, it may well be more advantageous from an economic, security, and societal perspective to seek protection from China in the form of a Chinese-led END.
Due to its comprehensive and longstanding security commitments with the United States, Australia would find it difficult to credibly detach from the US nuclear umbrella.
This type of framework could establish a balance of power akin to the Cold War era, thereby restoring regional nuclear deterrence. However, the Indo-Pacific might look more like a mosaic of different nations across various nuclear blocs rather than the bipolar division between Europe/the West and the USSR during the Cold War. For the United States, this setup would lower the costs associated with expanding END, but it might also require boosting its second-strike capabilities in the region by deploying additional nuclear submarines or platforms, rather than relying solely on traditional intercontinental ballistic missiles. It would also mean increasing its troop presence and basing within the Indo-Pacific. While it may create a balance of power, it is also extremely risky given that several of China’s friendly partners have unstable regimes and ongoing civil wars. More nuclear weapons do not necessarily reduce risk. Assuming rationality among these alternative END states carries its own risks.
This approach would be much more challenging for Australia. Due to its comprehensive and longstanding security commitments with the United States, Australia would find it difficult to credibly detach from the US nuclear umbrella.
US assumptions about END remain rooted in Cold War frameworks centred on a Euro-Atlantic core, with a peripheral Indo-Pacific network supporting it. This Western-centric approach has not evolved with the times, and the old assumptions underpinning the regional order are now fracturing. The nuclear architecture upon which the United States and its allies have long relied is therefore under growing strain. What was once a given in allied strategic postures is now a question mark. Without durable US support, the Indo-Pacific is increasingly reshaping the practice, politics, and psychology of END. The consequences will extend well beyond the region itself.
China’s nuclear modernisation has transformed Indo-Pacific deterrence. Over the past decade, Beijing has expanded its deterrent from a modest, land-based force to a significantly larger and more survivable second-strike capability. This evolution could influence military planning and diplomacy in the region as other states may reassess their own deterrence strategies in response to a more capable Chinese arsenal. Unlike Cold War superpower dynamics, deterrence now involves a web of strategic interactions. Changes in Chinese or North Korean capabilities shape regional threat perceptions and escalation risks.
For Indo-Pacific states, incentives to stay non-nuclear weaken as confidence in US nuclear guarantees fades and China advances its nuclear modernisation.
The traditional logic of nuclear ordering, largely shaped during the Cold War, cannot readily address the escalatory environment of the modern Indo-Pacific region. The risks of this strategic mismatch are serious, whether it is an uncontrolled nuclear cascade, competitive proliferation, or improvised nuclear-sharing deals that develop outside official frameworks. If reassurance fails and strategic anxieties grow, allies and regional states will adapt. In a setting with multiple nuclear powers and an increasing number of nuclear aspirants, the roles of Indo-Pacific allies, once considered peripheral in END frameworks, have become central to shaping modern nuclear dynamics.
For Indo-Pacific states, incentives to stay non-nuclear weaken as confidence in US nuclear guarantees fades and China advances its nuclear modernisation. These decisions on whether nuclear capabilities will meet deterrence needs and boost bargaining power are shaped by regional tensions and incentives just as much as by global factors.
Washington’s disinclination to meaningfully engage with Indo-Pacific states on nuclear issues strains US-led END and heightens anxieties about the credibility of US deterrence guarantees and the risks of abandonment and entanglement in crises. The ongoing debate among allies is whether the United States would be willing to sacrifice one of its cities to defend the capital of an allied nation under the nuclear umbrella. In 2026, this is certainly not a given.
About the authors
Marigold Black
Dr Marigold Black is a Researcher at RAND Australia.
Iain MacGillivray
Dr Iain MacGillivray is a Researcher at RAND Australia.
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