Nuclear proliferation in the Asia-Pacific
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Masako Ikegami, Leader of AMC Working Group "Nuclear Disarmament: Science, Technology & Geopolitics. Professor, School of Environment & Society, Tokyo Institute of Technology
On 1-5 November 2025 in Hiroshima, the 63rd Pugwash Conference “80 Years after the Atomic Bombing –Time for Peace, Dialogue and Nuclear Disarmament” was held to commemorate the 80th anniversary of the atomic bombings, as well as the 70th anniversary of the Russell-Einstein Manifesto, and the 30th anniversary of the Nobel Peace Prize to Sir Joseph Rotblat and Pugwash Conferences on Science and World Affairs. The author co-chaired the Working Group 3: Asia-Pacific and Nuclear Weapons, where committed participants from the region enjoyed frank and fruitful discussion. Inspired by these discussions, the below analysis highlights key present risks for nuclear proliferation in the Asia Pacific and concludes with a discussion on how to best manage these risks.
Nuclear-powered submarines, a potential risk of nuclear proliferation
While the world focuses on the wars in Ukraine and the Middle East, the security landscape in the Asia-Pacific is undergoing a fundamental structural shift. Such a shift would eventually erode the existing Non-proliferation of nuclear weapons (NPT) regime. The first trigger was Australia’s AUKUS agreement in 2021 with the U.S. and UK to acquire nuclear-powered submarines. AUKUS is a trilateral security partnership between Australia, the UK, and the U.S., intended to “promote a free and open Indo-Pacific”. The program would make Australia one of only seven nations to operate nuclear-powered submarines, along with the U.S., UK, France, Russia, China, and India. The agreement poses significant challenges to the NPT Treaty as it involves transferring weapon-grade uranium technologies. Although the NPT allows for the suspension of IAEA safeguards on nuclear material used in non-proscribed naval propulsion, critics are concerned this “safeguards loophole” could trigger a “Pandora's Box” where other nations follow suit, making it harder to police the distinction between peaceful and military nuclear programs.
Rising risk of nuclear proliferation in the Asia-Pacific
In late 2025, the U.S. approved South Korea to build nuclear-powered attack submarines. The U.S. also agreed to support South Korea's efforts in reprocessing and enrichment for peaceful, industrial purposes. Prior to these developments, a 2015 U.S.-South Korea nuclear pact, known as the 123 agreement, restricted South Korea from reprocessing, as it could potentially produce weapons-usable material. South Korea, by “charm offensive”, skillfully leveraged President Trump’s leadership style to clear complicated administrative processes of the State Department or IAEA safeguards criteria through Section 123 of the U.S. Atomic Energy Act (AEA). North Korea responded to the announcement by accusing the United States of giving South Korea the “green light” to become a “quasi-nuclear weapons state” in a Nov. 18 commentary in the state-run Korean Central News Agency (KCNA), and warned that Seoul’s submarine plan could trigger a “nuclear domino” effect. In response to the news, the Japanese defense minister said on Nov. 6 that Japan must consider adding nuclear-powered submarines to its fleet; developments in South Korea are adding momentum to the debate over Japan acquiring nuclear submarines. Indeed, “South Korea's nuclear submarine gamble raises prospect of underwater arms race in Asia”. Even in the civil sector, potential nuclear proliferation risks are increasing in Asia, as many Southeast Asian nations – Vietnam, Indonesia, Malaysia, Philippines – decide to introduce nuclear power.
Missile build up arms racing over Taiwan contingency risk
The Taiwan issue remains the key flashpoint in the region, intensifying military confrontation between China and the U.S. Nuclear risks exist during a potential Taiwan contingency, especially in inadvertent escalation involving dual-use systems (i.e. ballistic/hypersonic weapons with conventional or nuclear warheads) and/or inadvertent attacks on Nuclear Command, Control, and Communications (NC3) systems. China has unilaterally deployed massive medium-range/intermediate-range ballistic missiles over the past decades, as it was outside the Intermediate-Range Nuclear Forces (INF) Treaty between the U.S. and the Soviet/Russia. To counter China’s missile superiority, the U.S. and Japan have started building up missile forces. Since the INF Treaty expired in August 2019, to close the gap with China, the United States has been accelerating development of advanced missile systems such as the Typhon medium-range missile system which is capable of firing cruise missiles, including the Tomahawk of about 1,600 kilometers. The Japanese Self-Defense Forces have also been accelerating efforts to deploy and operate the improved, longer-range version of the Type 12 surface-to-ship missile for counterstrike capabilities. In facing China’s dominant missile forces, Japan, Australia, South Korea, Taiwan, and the United States (JASTU) are seeking to strengthen deterrence through the development of integrated air and missile defence (IAMD) capabilities.
Shifting focus from nuclear (non-)possession to no use of nuclear weapons
The Asia-Pacific region is witnessing an unprecedented arms race and nuclear proliferation risks. Nuclear proliferation risks are increasing across both civilian and military applications in the region. Due to geopolitical tensions, this trend seems inevitable. How can we solve this challenging issue? One practical solution would be to shift focus of nuclear disarmament efforts from nuclear (non-)possession to no-use of nuclear weapons. If no-use of nuclear weapons is consolidated institutionally as well as a universal value, nuclear weapons would be eventually of no use, only to be abolished universally. Thomas Schelling in his Nobel Prize lecture, “An astonishing sixty years; the legacy of Hiroshima” (8 December 2005), emphasized the essential value of a “stunning achievement” of the “attitude, or convention, or tradition, that took root and grew over these past five decades”, i.e. the inhibition of the use of nuclear weapons: “Preserving this tradition (inhibition) is as important as extending the NPT”. Referring to Iran and North Korea, Schelling reiterated that, while great efforts are required to suppress or discourage their interest in acquiring nuclear weapons, “equally great skill, or greater, will be required to create or enhance the expectations and institutions that inhibit the use of such weapons” (Ibid. 374). Schelling’s conclusion is the importance of the Comprehensive Test Ban Treaty (CTBT) that the U.S. Senate rejected in 1999:
“The symbolic effect of nearly 200 nations ratifying the CTBT, which is nominally only about testing, should add enormously to the convention that nuclear weapons are not to be used and that any nations that does use nuclear weapons will be judged the violator of the legacy of Hiroshima” (Ibid. 375)
The NPT has long been criticized as an unequal treaty only suppressing non-nuclear weapon states in terms of possession of nuclear technology or fissile materials (Article II, III), while no concrete measures are taken to ensure nuclear disarmament among nuclear-weapon states (Article VI). As Schelling emphasized, it is the CTBT which inhibits the use of nuclear weapons, whether for testing or in a real war, and this would be very effective to discourage existing or potential nuclear weapon states to acquire or expand their nuclear arsenals.
Eighty years after Hiroshima and Nagasaki, the Asia-Pacific faces mounting nuclear risks driven by new technologies, shifting alliances, and intensifying rivalries. Preserving and strengthening the global norm against the use of nuclear weapons, through instruments such as the CTBT and sustained dialogue, offers a pragmatic and urgent path toward reducing these dangers and keeping alive the legacy of Hiroshima.
"One practical solution would be to shift focus of nuclear disarmament efforts from nuclear (non-)possession to no-use of nuclear weapons."