Overview

The international environment surrounding nuclear weapons has never been more challenging. The most important factor shaping the international environment is the intensifying strategic confrontation between the United States on the one hand and China and Russia on the other. As these major powers deepen their rivalry, their nuclear policies increasingly reflect this adversarial tone.

China is currently the only one of the five nuclear weapons states recognized under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) that has been increasing its number of nuclear warheads, and it is diversifying its operational systems and enhancing its second-strike capability by building intercontinental ballistic missile (ICBM) silos, constructing strategic nuclear submarines, and developing new nuclear delivery systems such as hypersonic glider vehicles (HGVs). These moves to step up its nuclear capability and readiness to respond appear to contradict China's no-first-use policy for nuclear weapons and its minimum retaliation strategy of strategic deterrence with the minimum necessary retaliatory capability.

Since the preparatory stage of its invasion of Ukraine through to the present (November 2024), Russia has aimed to dissuade US and European support for Ukraine and limit their involvement in the conflict by indicating a reduced threshold for deploying nuclear weapons. This has been demonstrated through actions such as relocating nuclear forces during exercises, alluding to the restricted use of nuclear weapons, and making changes to its nuclear policy. In terms of capabilities, the modernization of Russia's nuclear forces is said to be in its final stages, although a new ICBM, the Sarmat, is reported to have failed a test in September 2024.

In its 2022 National Defense Strategy (NDS 2022), the US identified China as a "pacing challenge" that will set the tone of its national security strategy and Russia as a serious threat, and envisioned the nuclear forces needed to address the "two-peer" problem - simultaneously confronting nuclear threats from these two great powers while taking into account the risk of their strategic coordination. The "Strategic Posture Commission Report" released in October 2023 pointed out that the assumption in NDS 2022 of "winning one major war and deterring another" with conventional forces would lead to a force shortage in the future, and it referred to the need for effective nuclear retaliation options and deterrence posture at the regional level.

Thus, the US, China, and Russia increasingly recognize the role of nuclear capabilities in strengthening their security postures. At the regional level, the salience of nuclear weapons is rising. In East Asia, North Korea is advancing its development of ICBMs capable of reaching the US mainland and tactical nuclear weapons designed for combat use, signaling a growing reliance on nuclear weapons. In the Middle East, the fact that Israel, a suspected nuclear weapons state, and Iran, a potential nuclear power, have gone so far as to directly engage in warfare, albeit on a small scale, indicates that nuclear weapons are taking on greater significance in regional security.

US-Russia arms control prospects

The New Strategic Arms Reduction Treaty (New START Treaty) between the US and Russia must first be negotiated before the end of the five-year extension period in February 2026. However, Russia declared in February 2023 that it would suspend implementation of the treaty and President Putin stated in February 2024 that discussions on arms control would not resume as long as the US was trying to inflict a "strategic defeat" on Russia by supporting Ukraine. From Russia's perspective, this means that the US's response to the war in Ukraine is key. Although President-elect Trump has remarked that he would end the war in Ukraine immediately, the prospects for an early resolution and subsequent arms control negotiations remain uncertain.

Should negotiations between Russia and Ukraine proceed under Trump's leadership, arms control will emerge as one of the agenda items in broader strategic communications between the US and Russia. However, the diversification of delivery systems and differing views on European stability have rendered strategic stability increasingly complex, extending beyond the scope of New START's traditional focus on numerical control of strategic nuclear warheads and delivery systems. Finding an agreeable modality of arms control by addressing these challenges, including the treatment of non-strategic nuclear weapons and missile defense, will be difficult.

US-China arms control prospects

As for arms control between the US and China, the latter continues to show a negative attitude toward arms control talks, and no progress will be made for the time being. For China, restrictions on the buildup of its nuclear capability would lock in the asymmetry of forces between the two countries and risk perpetuating its vulnerability. Transparency measures such as mutual declarations of nuclear forces' quantity, deployment, and operational status would further expose China to potential US attacks.

On the other hand, however, President-elect Trump's transactional approach may open avenues for easing tensions over nuclear deterrence and arms control if China offers a reasonable economic quid pro quo. While reducing tensions between the US and China is generally desirable, détente could grant China greater freedom of action in East Asia that could jeopardize Japan's security. Improving the US-China relationship and reducing threats through arms control must be pursued in conjunction with maintaining the credibility of the US-Japan alliance.

In addition, China is likely to continue voicing concerns about the AUKUS initiative to provide nuclear attack submarines to Australia (AUKUS Pillar I) at various multilateral forums, including the NPT Review Conference and the International Atomic Energy Agency (IAEA) General Conference. It raises the issue of safeguards for the transfer of highly enriched uranium, the fuel used to power nuclear submarine reactors, and maintains a firm stance to keep US-UK-Australia collaboration in check.

Increasing uncertainty surrounding North Korea and Iran issues

In the area of nuclear nonproliferation, the focus will continue to be on North Korea's growing nuclear capabilities and Iran's escalating nuclear program.

Regarding North Korea, President-elect Trump stated during the election campaign that he would stop missile launches through discussions with Kim Jong-un, and it is believed that the US under President Trump will pursue an arms control-based approach that focuses on reducing the nuclear threat rather than eliminating nuclear weapons, i.e., denuclearization. If the Trump administration were to de facto acquiesce to North Korea's possession of nuclear weapons and if there were no agreement among the US, Japan and South Korea on the impact of this on Japanese and Korean security, then US-North Korea dialogue, otherwise desirable in terms of threat reduction, could exacerbate Japan's anxiety over extended nuclear deterrence and reassurance.

The previous Trump administration took a hardline stance against Iran's nuclear program, withdrawing from the Joint Comprehensive Plan of Action (JCPOA) and re-imposing sanctions in 2018, and killing Islamic Revolutionary Guard Corps commander Qasem Soleimani in 2020. Masoud Pezeshkian, who is seen as an internationalist, has assumed the presidency in Iran, and Abbas Araqhchi, who has overseen JCPOA negotiations, has been appointed as foreign minister. However, distrust of the US, which unilaterally reneged on its commitments under the JCPOA, is deep-rooted within Iran, and it will be difficult to build trust between Iran and the US. Furthermore, UN Security Council Resolution 2231, which was adopted along with the JCPOA and which suspended sanctions based on past Security Council resolutions, will expire on October 18, 2025. This would allow the West to reinstate sanctions based on past Security Council resolutions, and strong Iranian opposition can naturally be foreseen. An escalation of the confrontation could bring Iran closer to possessing nuclear weapons and push Iran even closer to China and Russia.

As part of the review process for the NPT, the cornerstone of the nuclear nonproliferation regime, the Preparatory Committee for the 2026 NPT Review Conference will be holding a third meeting in 2025 but, in the wake of this strategic competition among the major powers, disputes over the narrative of "who ruins the nonproliferation regime?" will likely continue here. As things stand, it is unlikely that a final document will be adopted by consensus. While some countries in the "Global South" have refrained from condemning Russia's aggression against Ukraine as a violation of international law, this position can partly be attributed to their antipathy against the US- and Western-led international order and their aspiration for a more multipolar world.

Recommendations

• Japan will first need to carefully assess whether President Trump in his second term will adopt confrontational or conciliatory postures in the US's strategic relationships with other major powers. In any case, Japan should take steps to make the alliance robust and establish a stronger alliance deterrence posture. Japan and South Korea should also seek closer policy coordination and cooperation with the US in order to make deterrence more reliable and design contingency plans covering Taiwan and the Korean Peninsula. In this context, the US, Japan and South Korea should establish a common understanding of the role of nuclear weapons and build capabilities optimal for responding to contingencies. Japan also should explore the possibility of confidence building and threat reduction through strategic dialogue with China and other countries.
• On the other hand, the US pursuing an "America First" policy in the NPT-centered nuclear nonpro liferation regime would only serve to aggravate the friction between the Global South and the West. The weakening of the nuclear nonproliferation regime and the spread of an anti-Western atmosphere to the regime itself through the escalation of such a confrontation could provide an opening for China, Russia, and other countries to expand their influence. To reduce this risk, Japan needs to be more actively involved in multilateral diplomacy and play a role in keeping the US tied to the international community.
• In any case, the greatest concern is the growing policy discrepancy between the US and Japan. It will be important for Japan to urge the US to join with it in addressing nuclear issues such as deterrence, arms control, disarmament, and non-proliferation in a coordinated way as a form of crisis management in response to growing uncertainty. This should be pursued as an integral part of a security strategy, with close coordination to ensure a cooperative and unified policy approach.

(December 11, 2024)