Former Japanese Prime Minister Ishiba Shigeru delivered a keynote address at the Asan Plenum 2026, hosted by The Asan Institute for Policy Studies, underscoring the evolving role of alliances amid a rapidly changing security environment and calling for deeper and more effective cooperation among allies.

In his keynote speech, Ishiba outlined five key issues shaping the future of regional security: deterrence against North Korea, nuclear sharing, responses to a Taiwan Strait contingency, the prospect of an Asia-Pacific collective security framework, and the strengthening of Korea–Japan security cooperation. He provided a comprehensive assessment of the strategic trajectory of Northeast Asia and the broader Indo-Pacific.

On North Korea, Ishiba noted the continued advancement of Pyongyang’s nuclear and missile capabilities, emphasizing that deterrence must go beyond punitive retaliation to include robust denial capabilities that can effectively limit damage. Given North Korea’s improving ability to conduct saturation attacks and deploy high-speed, maneuverable missiles, he stressed that strengthening missile defense and civil defense capabilities is an urgent priority. He further underscored the need to significantly enhance strategic coordination among Korea, the United States, and Japan.

Addressing nuclear sharing, Ishiba pointed to the growing policy debate in South Korea, including discussions on indigenous nuclear capabilities and nuclear sharing arrangements. He explained that nuclear sharing need not be limited to the physical deployment of nuclear weapons, but could also involve sharing decision-making processes leading to nuclear use, as well as risk-sharing mechanisms. Such arrangements, he argued, would help enhance the credibility of nuclear deterrence, including extended deterrence.

On a potential Taiwan Strait contingency, Ishiba assessed that China would likely seek to avoid direct conflict with Japan in order to prevent escalation involving the U.S.-Japan alliance. However, he warned that U.S. military operations would inevitably involve bases in Japan, raising complex political and strategic considerations. He further cautioned that the simultaneous occurrence of crises in the Taiwan Strait and on the Korean Peninsula represents the most dangerous scenario, underscoring the need for closer strategic coordination among allies to prevent such an outcome.

Turning to the concept of an “Asian NATO,” Ishiba presented several possible models, emphasizing that strengthening a “lattice-like” network of security cooperation among U.S. allies in the region is the most realistic approach. He noted that deeper integration among countries such as Korea, Japan, Australia, and the Philippines could serve as a foundation for a future regional collective security framework.

On Korea–Japan security cooperation, Ishiba stressed that the growing strategic alignment among China, Russia, and North Korea makes closer bilateral coordination increasingly important. He identified the conclusion of a Korea–Japan Acquisition and Cross-Servicing Agreement (ACSA) as a key priority and called for the institutionalization of practical cooperation between the two countries. He also addressed developments in the Middle East, noting that potential disruptions such as a closure of the Strait of Hormuz would pose a threat to global order and should be addressed through a multinational response based on United Nations resolutions.

In closing, Ishiba highlighted the historical ties between Korea and Japan and expressed hope that both countries would deepen strategic dialogue and expand cooperation. He emphasized that closer Korea–Japan collaboration will be essential not only for regional stability in the Indo-Pacific but also for maintaining global peace and order.

The Asan Plenum 2026, held on April 8 at the Grand Hyatt Seoul, convened leading policymakers, military officials, and experts to discuss the future of alliances in an era of intensifying geopolitical competition.

* Attachment: Full text of Keynote Speech by Former Prime Minister Ishiba Shigeru (Unofficial English translation)