The Indo-Pacific is entering a far more dangerous strategic era. Military modernization, grey-zone coercion, and rapid nuclear expansion are reshaping the regional balance of power. Most notably, China is undertaking a historic expansion of its nuclear arsenal, investing in silo fields, road-mobile intercontinental ballistic missiles, ballistic missile submarines, and dual-capable systems. Simultaneously, Russia’s willingness to use nuclear threats in Europe demonstrates that nuclear coercion is once again central to great-power competition.

In Washington, proposals such as Ely Ratner’s Pacific Defense Pact reflect recognition that the current security architecture is insufficient. A more formalized collective defense structure in the Indo-Pacific is necessary.

However, this is not sufficient. A conventional Pacific Defense Pact does not fully address the most dangerous level of escalation to large-scale conventional war or nuclear attack. What the region now requires is a narrowly defined Indo-Pacific nuclear alliance.

A Narrow, Explicit Purpose

This would not be a sweeping defense pact covering every maritime incident, border clash, cyber intrusion, or grey-zone coercive act. It would have a clear and carefully delimited purpose. That is to deter large-scale conventional war or nuclear attack against member states.

Its clarity would be its strength. That clarity performs a second vital function. It minimizes the risk of entrapment by ensuring member states are not dragged into escalation over actions below the threshold of war. By explicitly excluding grey-zone coercion and limited crises from its nuclear remit, the alliance would reassure leaders that only truly existential threats trigger its highest-level commitments.

Participation becomes politically sustainable and strategically credible because it avoids automatic escalation over incremental provocations. The alliance would draw a line at catastrophic strategic aggression.

The Historical Record: Why Nuclear Deterrence Matters

The case for a nuclear alliance is not theoretical. It is grounded in historical experience. During the Cold War, nuclear parity between the United States and the Soviet Union prevented direct large-scale war and nuclear attack in Europe. Despite ideological confrontation and proxy conflicts, neither side attempted a conventional war or nuclear attack on the other’s core territories. Nuclear weapons imposed restraint. They deterred not just nuclear use, but overwhelming conventional assault.

Similarly, within NATO, the presence of U.S. nuclear guarantees has prevented full-scale Russian conventional attack on Alliance territory. Moscow has tested boundaries through

hybrid tactics and coercive signaling, but it has not launched a large-scale attack on NATO soil. Nuclear deterrence at the alliance level raised the costs to an unacceptable threshold.

The 1969 Sino-Soviet border conflict further illustrates how nuclear capability constrains escalation. The Soviet Union’s nuclear superiority allowed it to signal credible threats, while China’s emerging nuclear capability and mobilization signaled resolve. Mutual fear of escalation compelled negotiation, including intervention through U.S. triangular diplomacy. Nuclear weapons shaped behaviors without being used.

The India–Pakistan experience is equally instructive. Prior to overt nuclearization, the two states fought multiple full-scale wars. Since their nuclear tests in 1998, crises have erupted, but they have remained limited. Missile strikes, cross-border skirmishes, and periods of great tension have not escalated into all-out conventional war or nuclear attack. Nuclear deterrence imposed a ceiling on the conflicts.

Contrast this with the Russia–Ukraine war. Ukraine relinquished its nuclear arsenal in the 1990s and now confronts a nuclear-armed Russia without possessing its own nuclear deterrent. The result has been a prolonged and costly conventional war of attrition. The absence of mutual nuclear deterrence has made sustained large-scale conventional war possible. By comparison, Russia has not launched a direct assault on NATO territory precisely because nuclear deterrence underwrites NATO’s collective defense.

The pattern is clear. Where credible nuclear deterrence exists between adversaries, large-scale conventional war and nuclear attack is sharply constrained or avoided. Where it does not, prolonged and devastating large-scale conventional war and nuclear attack becomes more likely.

The Indo-Pacific Strategic Gap

The Indo-Pacific currently relies on a patchwork of bilateral extended deterrence arrangements centered primarily on Washington. These remain essential, but they are increasingly strained or at risk of being fractured by China.

China’s expanding nuclear arsenal complicates escalation management. A larger and more survivable force reduces the credibility of assumptions that escalation will remain controlled or asymmetrical. Meanwhile, the region contains multiple flashpoints, including Taiwan, the South China Sea, the Korean Peninsula, and the India–China border where conventional conflict could rapidly climb the escalation ladder.

Frameworks like AUKUS and the Quad strengthen capabilities and coordination, while the proposed Pacific Defense Pact aims to guarantee that the U.S. and its allies can act in concert during crises or conflicts. But they are not structured as nuclear deterrence mechanisms. They do not institutionalize shared nuclear declaratory policy, crisis consultation at the strategic level, or joint planning for high-end escalation management. A nuclear alliance would fill that gap.

Beyond a Pacific Defense Pact

A Pacific Defense Pact, as envisioned in conventional terms, strengthens interoperability and signals unity. But without an explicit nuclear dimension, it leaves ambiguity at the highest rung of escalation. That ambiguity can invite miscalculation.

A nuclear alliance would not broaden commitments; it would sharpen them. It would: (1) establish shared declaratory policy on deterrence of large-scale war and nuclear attack, (2) institutionalize strategic consultation mechanisms during crises, (3) coordinate planning to ensure credible escalation management, and (4) reinforce extended deterrence while discouraging independent nuclear proliferation.

Importantly, such an alliance need not require additional states to acquire nuclear weapons. Like NATO, it could rely on extended deterrence commitments and nuclear-sharing with structured burden-sharing and planning arrangements. Nuclear forces may remain nationally controlled, but alliance cohesion amplifies deterrent credibility. 

Clarity as Stability

The objective is not confrontation. It is clarity. By defining a narrow and explicit threshold—large-scale conventional war or nuclear attack—the alliance reduces the risk of catastrophic miscalculation. It signals to potential aggressors that existential aggression will trigger unified strategic consequences.

Simultaneously, it reassures members that lower-level competition will not automatically escalate to nuclear commitments. This dual clarity strengthens deterrence at the top end and stabilizes politics at the lower end.

A Necessary Evolution

The Indo-Pacific is now the central arena of 21st-century strategic competition. Nuclear modernization is accelerating. Multi-nuclear dynamics are emerging. Escalation timelines are compressing.

History shows that nuclear weapons, and when embedded within credible alliance structures, deter catastrophic war. They prevent large-scale conventional war and nuclear attacks not because they are desirable tools of war, but because they impose unacceptable costs on those who contemplate it.

A Pacific Defense Pact is a step forward, but in the current strategic environment, it is not enough. To deter large-scale conventional war and nuclear attack in the Indo-Pacific, the region must move beyond a Pacific Defense Pact. It must build a nuclear alliance.

Natalie Treloar is the Australian Company Director of Alpha-India Consultancy, a Senior Fellow at the Indo-Pacific Studies Center (IPSC), a Senior Analyst at the National Institute for Deterrence Studies (NIDS), and a member of the Open Nuclear Network. Views expressed in this article are the author’s own.

Beyond a Pacific Defense Pact: Why the Indo-Pacific Requires a Nuclear Alliance was originally published on Global Security Review.

The existing US-led hub-and-spoke alliance system in the Asia-Pacific is fundamentally different than the North Atlantic Treaty Organization (NATO). In the 1950s the US investigated the possibility of establishing a regional multilateral alliance, but this soon proved infeasible. Unable to forge a Northeast Asian equivalent to NATO at the onset of the Cold War, the US opted instead for the “hub-and-spoke” architecture, where the spokes radiate out from Washington in a network of asymmetrical ties reinforcing American regional dominance. Why?

First, compared to Europe, the Asia-Pacific has very little history of multilateral institutions and alliance formation. Modern European states have a history of doing so dating back well before the Treaty of Westphalia was established in 1648. European sovereign political systems emerged out of Westphalia; Europe came to develop different notions of international community and international order, based, in part, on the concept of international law. Asia did not have such a tradition of legalistic international agreements.

Second, geography also plays a significant role in the nature of warfare, and therefore the ability of countries to come to one another’s aid. European nations border each other, but they do so in a land context. As such, not only is it easier to move around troops and military equipment, but it is faster.

The nature of geography and distance also inform countries’ threat perceptions. NATO continues to endure because of a shared common adversary—Russia. Countries neighbor each other, making for an easily delineated bloc. The distances between Southeast Asia and Northeast Asia are formidable compared to Europe. Moreover, the sheer size of China, and the formidable military power of Japan, made it harder for smaller competitors to balance against them.

There were some attempts at bridging East and West. In 1954, the Southeast Asia Treaty Organisation (SEATO) was established because of the Southeast Asia Collective Defence Treaty. It included Australia, France, New Zealand, Pakistan, the Philippines, Thailand, the United Kingdom, and the US and was designed to curb the spread of communism in Asia. A major reason SEATO failed and was disbanded in 1977 was because there was a lack of a common threat perception.

What did survive was the U.S. hub-and-spoke system: the US-Japan alliance as a means of curbing any potential regional Japanese aggression after World War II, the US- South Korea alliance to protect South Korea from a North Korean invasion, and the US alliance with Australia and New Zealand (ANZUS) to protect both nations from perceived threats of communist invasion by China and Indonesia.

Central and critical to the credibility of any alliance system is how it deters conflict. This is arguably much harder to achieve in a multilateral alliance than in the current hub-and-spoke system. Conventional deterrence in the Asian maritime theater is difficult. The most significant work on conventional deterrence was done by John Mearsheimer. However, Mearsheimer’s analysis may be persuasive for eras preceding the development of nuclear weapons, but the pre-nuclear era did not involve missiles. His analysis was based on a European land context, not an Asian maritime context. As such, thinking on conventional deterrence is incomplete.

There are significant logistical challenges that come with trying to establish a multilateral alliance system in Asia. Tasks include the need to ensure the prompt replenishment of destroyed combat ships, establish defensive perimeters for fleet support, and ensure the safety of fleet replenishment oilers and dry cargo/ammunition supply ships, just to name a few.

Budget constraints brought on by sequestration (2013), coupled with longer-term financial uncertainty, was raising questions about the US Navy’s Military Sealift Command and its combat logistics force more than a decade ago. Europe was, and remains, one single geostrategic entity connected by an excellent road network. In the Asia-Pacific, Australia, Japan, South Korea, and Taiwan are more dispersed, with neutral and non-aligned states between them, not to mention a growing Chinese submarine fleet.

American forces need to move around large numbers of ships, aircraft, troops, and munitions. Unless the US establishes more permanent bases on allied territory, it is not clear that the US is able to adequately deploy replacement capabilities on very short notice, especially once conflict breaks out. Whilst American declaratory policy that requires a defense of allies in Asia is sound, it needs to be backed up by raw capability, the two components of deterrence.

For more than a decade, analysts have encouraged the US to improve readiness and sustainment of the US Navy. In 2014, the Center for Strategic and Budgetary Assessments warned of many more similar issues, including how quickly cruisers and destroyers exhaust their missiles and how adversaries will attempt to use “cheap” missiles (such as the BrahMos cruise missile) to attack US warships to get them to use their most effective defenses first,  such as the long-range SM-6 missile, and then strike with more effective weapons to destroy carriers and their escorts.

The foundation of power projection was and remains sea control. As Hugh White argues, what has contributed to making the US such a decisive power in the region is a robust sea-control capacity with low risk, and therefore little cost. The modern concept of sea control has its origins in the writings of Rear Admiral Alfred Thayer Mahan. Sea control was about naval superiority, the concentration of forces, and decisive battles.

Sea control is the condition in which one has freedom of action in specified areas and for specified periods of time and, where necessary, to deny or limit its use to the enemy. Sea control is different from sea denial. The latter refers to attempts to deny an adversary’s ability to use the sea without necessarily seeking to control the sea. When it comes to Asia, China and the United States are gradually trading places when it comes to sea control.

Discussions about a multilateral alliance would arguably have to address the unavoidable question of nuclear weapons and extended nuclear deterrence (END). Discussions within NATO’s Nuclear Planning Group during the Cold War about targeting and basing helped calm nervous allies, helped hold NATO together, and, in some cases, helped stem the tide of proliferation.

Both the US–Republic of Korea Extended Deterrence Policy Committee (EDPC) and the US–Japan Extended Deterrence Dialogue were established after the 2010 Nuclear Posture Review for a similar purpose. There were growing concerns around the ability of the US to overcome China’s anti-access/area-denial capabilities and American support in the event of specific contingencies involving the disputed Senkaku/Diaoyu Islands in the East China Sea. Could these bilateral dialogues become multilateral fora? This applies just as much to conventional weapons, but where the members of the alliance are far apart from each other, the potential red lines of escalation and conflict are much less identifiable than they would be in a land context.

But the technical challenges in the credibility of American extended deterrence to Australia, Japan, and South Korea matter less than the reasons why the US would want to do nuclear strategy again, this time in East Asia, a vastly more complicated theater. What matters is interest.

Hugh White raised the uncomfortable but critical issue when he suggested that Tokyo’s desire for a closer defense relationship with Australia is all about lining Australia up to support Japan against China, and that is the way Washington and Beijing will see it, too. Tokyo and Washington believe that Australia should defend the US-led international order and refuse concessions to China’s ambitions. Australians have not decided whether they agree with the US and Japan and are predisposed to seek a compromise with China—all while retaining a strong American role.

As White argued, no possible US nuclear posture, even the best possible, would eliminate the risk that a conflict with a nuclear-armed great power like China might lead to direct nuclear attacks on US territory. This leaves America’s East Asian allies to ponder whether American interests in the Western Pacific are strong enough for Washington to justify running the risk of conflict going nuclear.

Professor Paul Bracken of Yale University expressed concerns about American alliances in Asia. He found it nearly inconceivable that the US would actually use nuclear weapons to defend Australia, Japan, or Taiwan. Bracken noted that he played out countless scenarios, and that when it came down to it, American leaders were unwilling to use nuclear weapons. Bracken went so far as to suggest that the United States may not engage in a conventional hi-tech war with China, either.

Ely Ratner’s article is thought-provoking, valuable, and timely. But there are significant challenges in alliance credibility in Asia, because interests do not align as easily as they do in Europe. As former US Secretary of State John Foster Dulles remarked in 1952, “The North Atlantic Treaty reflected a sense of common destiny as between the peoples of the west, which grew out of a community of race, religion, and political institutions, before it was finalised. But that element does not clearly exist as yet anywhere in the Pacific area.” The same is true today, seven decades later.

Christine Leah, PhD, is a fellow at the National Institute for Deterrence Studies.  

American Alliances in East Asia: An Australian Perspective was originally published on Global Security Review.