Japan's Defense Transformation Accelerates: The Operational Deployment of Stand-Off Defense Capabilities and the Historical Reconstruction of the Security System

On April 27, 2026, Prime Minister Sanae Takaichi launched a panel of experts aimed at reviewing security and defense policies. Amid the simultaneous military pressures from China, North Korea, and Russia, Japan's defense policy is facing the most significant turning point since the end of World War II. This panel is positioned as a means to further advance the "Three Security-Related Documents" formulated in 2022—National Security Strategy, National Defense Strategy, and Defense Build-Up Program—implying an intention not merely to review but to fundamentally redesign Japan's security framework.

The backdrop of this movement is a groundbreaking deployment that took place at the Kumamoto-based Kengun Garrison in March 2026. The Japan Ground Self-Defense Force has operationally deployed the latest Type 25 Surface-to-Ship Missile (Type 25 SSM) here. This missile has significantly extended its range from approximately 200 km with the previous Type 12 SSM to about 1,000 km with the Type 25. This range covers a wide area from Kyushu to the East China Sea, effectively reaching parts of mainland China. Defense Minister Shinjiro Koizumi stated during the deployment, "Japan is facing the most severe and complex security environment since the end of World War II," emphasizing the necessity of enhancing stand-off defense capabilities.

The Type 25 SSM embodies a technological leap that goes beyond mere range extension. Its airframe design, considering low detectability (stealth), makes it difficult for enemy radar to detect, and the "Update-to-Date Command (UTDC)" function allows for mid-flight target reprogramming via satellite communication. The dynamic response capability against moving maritime targets provides operational flexibility that is on a different level compared to traditional fixed-target attack missiles. Additionally, derivative models for ship-launch and air-launch are under development, with deployments planned for fiscal year 2028. The ship-launch variant is to be integrated into the Japan Maritime Self-Defense Force's escort ship "Teruzuki" (based in Yokosuka), while the air-launch variant is planned for integration with the F-2 support fighter at Hyakuri Air Base in Ibaraki Prefecture.

This stand-off defense concept is positioned within a lineage that began with the 2018 "Defense Program Guidelines" and "Medium-Term Defense Force Build-Up Program." At that time, the emphasis was placed on strengthening defense posture in the southwestern islands due to concerns over China's rapid military expansion. In December 2020, a cabinet decision was made regarding "the establishment of a new missile defense system and the enhancement of stand-off defense capabilities," officially approving the development of an upgraded version of the Type 12 SSM. The security documents of December 2022 legally formalized the deployment of ground-launched and ship-launched stand-off missiles by fiscal year 2027. The Type 25 SSM is precisely the core system of this ground-launched category.

However, the Ministry of Defense's vision does not stop with the Type 25. The Acquisition, Technology & Logistics Agency (ATLA) is currently advancing the development of next-generation systems aimed at the second phase (2027-2032). One of these is the "new type of surface-to-ship and surface-to-ground precision-guided missile." This system, which began development in 2025, is equipped with guidance accuracy and penetration capabilities that surpass those of the Type 25 SSM, possessing attack capabilities against not only maritime targets but also critical ground targets such as airfields, ports, and command and control facilities. This represents a technological evolution that directly relates to the legal and political discussions on how far Japan can expand the concept of "counterattack capability" within the framework of "defensive defense."

Furthermore, noteworthy is the development of hypersonic guided missiles and high-speed glide vehicles (HVGV). ATLA has already conducted multiple demonstration tests of hypersonic technology, aiming for practical application in the early 2030s. If these systems are operationally deployed, Japan will establish a multi-layered anti-access/area denial (A2/AD) capability along the First Island Chain. This is positioned as complementary to the deterrence provided by U.S. forces in Japan, but it also encompasses the aspect of building "self-imposed deterrence" amid wavering trust in U.S. security commitments.

In fact, within Japan's security community, the "shaking of trust in the U.S. security umbrella" has become apparent. Kazuto Suzuki, director of the Security and Economy Research Institute, points out, "The defense posture has completely shifted southwest. The priority for the north has significantly decreased compared to before." The defense budget for fiscal year 2026 is expected to reach a record high of $58 billion, much of which is allocated to building this "southern shield." The southwestern islands stretch within 100 km from Kyushu to Taiwan, forming a natural barrier that is central to the First Island Chain strategy, separating the East China Sea from the Philippine Sea.

This large-scale defense transformation is also sparking debate within Japan. The renaming of the Self-Defense Forces' rank titles to military standards symbolizes the widening gap between the principle of "defensive defense" and the reality of the Self-Defense Forces. In the vicinity of the Fuji Garrison in Shizuoka Prefecture, local residents are divided in their opinions regarding missile deployments, and active discussions continue regarding the appropriateness of a defense budget on the scale of 100 trillion won.

On the other hand, Japan-South Korea defense cooperation is also showing significant progress. Defense Minister Koizumi is scheduled to visit South Korea in late June to meet with South Korean Minister of National Defense Lee Jong-sup. This will be Koizumi's first visit to South Korea since taking office. During Lee's visit to Japan in February 2026, both agreed to deepen security cooperation, and a deputy-level "2+2" meeting of foreign and defense officials is also planned for early May. Furthermore, it is noteworthy that in January 2026, the Japan Air Self-Defense Force provided air-to-air refueling support to South Korean military aircraft. This suggests that practical-level cooperation has already begun, surpassing institutional agreements. However, within South Korea, skepticism towards military cooperation with Japan remains deeply rooted due to historical circumstances stemming from Japan's colonial rule.

When evaluating this series of movements comprehensively, it becomes clear that Japan is transitioning the substance of its legal framework of "defensive defense" towards "proactive deterrence." The 1,000 km range of the Type 25 SSM, the UTDC capability, the ground attack capabilities of next-generation precision-guided missiles, and the development of hypersonic weapons—all of these are being advanced under the name of "defense," yet their capabilities possess a dual nature that can be repurposed for offensive operations. How the expert panel under the Takaichi administration addresses this legal contradiction, and how the redefinition of the Japan-U.S. alliance and the deepening of Japan-South Korea cooperation interrelate, will likely be key factors influencing the future of security in Northeast Asia.