On May 21, the G-7 Summit concluded its three-day meeting in Hiroshima, Japan. Prime Minister Kishida Fumio chose his hometown – the first city in the world to suffer a nuclear bombing – as the host city with the determination to promote a world without nuclear weapons. At the summit, the G-7 leaders issued a joint statement entitled “Hiroshima Vision on Nuclear Disarmament,” which Kishida said was of “historic significance.”
The Hiroshima Vision reaffirmed the commitment to “achieving a world without nuclear weapons with undiminished security for all” and outlined “a realistic, pragmatic, and responsible approach” to this end, such as maintaining the record of nuclear non-use, the continued decline in global nuclear arsenals, and a moratorium on nuclear testing and fissile material production for weapons purposes. The vision also promoted nuclear transparency, the entry into force of the Comprehensive Nuclear Test Ban Treaty (CTBT) and the Fissile Material Cut-off Treaty (FMCT), and disarmament and non-proliferation education. These proposed measures all, by and large, align with Japan’s Hiroshima Action Plan, announced by Kishida at the NPT Review Conference in August 2022.
While the Hiroshima Vision was surely significant in various respects, advocates for nuclear abolition, including hibakusha (survivors of the atomic bombings in 1945), criticized the document, pointing out that it failed to show concrete steps toward a world without nuclear weapons and did not even refer to the Treaty on the Prohibition of Nuclear Weapons (TPNW).
Along with the Hiroshima Action Plan, the Hiroshima Vision will serve as the foundation for Japan’s future nuclear disarmament efforts. However, Japan’s approach to nuclear disarmament as outlined in these statements requires Tokyo to navigate two difficult dilemmas.
One looming dilemma is between committing to the continued decline of nuclear arsenals worldwide and supporting the future development of the U.S. nuclear program to ensure the credibility of U.S. extended nuclear deterrence. This point appeared in the Hiroshima Vision in the form of concern about Russia’s nuclear saber-rattling and China’s accelerated nuclear expansion, among others.
With the rise of China as a second nuclear peer, which is expected to field about 1,500 warheads by 2035, and Russia’s defiance of bilateral arms control regimes, the United States has witnessed an emerging discussion of the “two-peer” problem – that is, as the former U.S. STRATCOM commander put it, “For the first time in history, the nation is facing two potential strategic peer, nuclear-capable adversaries at the same time, who must be deterred differently.” This two-peer debate is leading to growing domestic calls for expanding the U.S. nuclear arsenal.
The Republican leaders of the House and Senate Armed Services Committees, for example, have said that the United States has no time to waste in developing a nuclear posture that can deter both China and Russia, which means “higher numbers and new capabilities.” Indeed, a recent report by the Center for Global Security Research recommended that Washington redeploy additional nuclear warheads from its reserve when the New START Treaty expires in February 2026 without a follow-on agreement, and develop sea-launched nuclear cruise missiles to strengthen the U.S. extended nuclear deterrent. The report also suggested that the necessary decisions and investments should be made now in case a larger U.S. nuclear force is needed in the future.
If Washington does move to expand its nuclear arsenal, Tokyo will have to decide whether to endorse this policy shift. However, supporting U.S. nuclear expansion would contradict the Hiroshima Vision’s statement that “the overall decline in global nuclear arsenals achieved since the end of the Cold War must continue and not be reversed.” A U.S. decision to expand its nuclear arsenal could, furthermore, escalate a nuclear arms race with China and Russia. Some hope that the G-7’s agreed commitment to the continued decline of nuclear arsenals might help curb this momentum in Washington, but this could potentially undermine U.S. extended nuclear deterrence.
Faced with this dilemma, Japan would have to decide whether to support, oppose, or remain silent on the future U.S. nuclear program. Japan’s embrace of U.S. nuclear expansion could amplify the domestic U.S. calls for more nuclear weapons, as has happened in the past. For example, Tokyo’s security concerns and lobbying with the former Obama administration reportedly raised controversy over whether to retire nuclear-armed Tomahawk missiles.
The second dilemma relates to Japan’s position on the TPNW. While the Hiroshima Vision stated that it aimed to promote the “realities of nuclear weapons use,” it avoided using the phrase “humanitarian consequences of nuclear weapons use” advocated by TPNW proponents. The same phrase, “realities of nuclear weapons use,” was also used in the Hiroshima Action Plan. This suggests that Japan has been cautious about its language for fear that showing support for the TPNW may strain Japan-U.S. relations. Indeed, Washington has occasionally issued warnings to its nuclear allies, such as Japan, Australia, and NATO states, when they take steps to move closer to the TPNW.
On the other hand, as the sole country to have experienced wartime atomic bombings in Hiroshima and Nagasaki, Japan is expected to take a leading role in highlighting the humanitarian consequences of nuclear weapons and advocating their abolition. International and domestic pressure to support humanitarian approaches and the TPNW has been mounting, as nuclear abolitionists have become increasingly dissatisfied with the progress of nuclear disarmament under the NPT regime. This has been fueled by the failure to adopt a consensus document at the last NPT Review Conference and by activists’ disappointment with the Hiroshima Vision at the G-7 this time.
This dilemma has shaped recent Japanese decisions on nuclear disarmament. For example, unlike some NATO states, the Japanese government decided not to participate as an observer in the First Meeting of States Parties to the TPNW, while Tokyo sent its officials to the Conference on the Humanitarian Impact of Nuclear Weapons a day earlier. At the NPT Review Conference, Kishida refrained from using humanitarian language in his Hiroshima Action Plan, while Japan, unlike other U.S. nuclear allies, supported the Joint Humanitarian Statement delivered by Costa Rica.
This mixed Japanese position is also manifested in Kishida’s general stance on the TPNW, which he considers “an important treaty that can serve as an exit” to realize a world without nuclear weapons. In this regard, Japan will have to make a decision on whether to support humanitarian statements in the upcoming NPT Preparatory Committee and/or to participate as an observer in the Second Meeting of the TPNW in the near future.
These two dilemmas reflect the long-standing challenge of balancing nuclear disarmament and nuclear deterrence, which the Japanese government has been trying to reconcile. Unfortunately, this dichotomy is likely to become even more striking as a result of the deteriorating international security environment on the one hand, and the increasing demands for supporting the TPNW on the other hand. Faced with these opposing dynamics, Japan will have to navigate a challenging path toward a world without nuclear weapons.