Deployment of Japan's Long-Range Missiles Triggers Constitutional Controversy: A Turning Point for the "Defensive Defense" Principle

On March 31, 2026, Japan's Defense Minister Shinjiro Koizumi announced the formal deployment of long-range missiles with "capability to attack enemy bases" at the Kengun Garrison in Kumamoto Prefecture and the Fuji Garrison in Shizuoka Prefecture. This marks the first deployment of offensive weapon systems by the Japan Self-Defense Forces (JSDF) with a range exceeding 1,000 kilometers, a move that has sparked intense controversy within Japan and is widely seen as a significant shift from Japan's post-war "exclusively defense-oriented" policy.

The two missile systems being deployed are the "Type 25 Anti-Ship Missile" and the "Type 25 Hypersonic Glide Vehicle," both of which have ranges exceeding 1,000 kilometers. According to the Japanese Ministry of Defense's plan, this is just the beginning of a nationwide deployment, with plans to gradually expand these long-range strike capabilities to more garrisons in the future. The deployment of these weapon systems means that the JSDF now possesses the technical capability to preemptively strike enemy bases before being attacked on home soil.

From a legal perspective, this deployment touches on the core issues of Article 9 of the Japanese Constitution. This article explicitly states that Japan renounces war as a means of settling international disputes and does not maintain land, sea, and air forces or other war potential. For decades after the war, the Japanese government has interpreted the existence of the Self-Defense Forces as "the minimum necessary power for self-defense" and has adhered to the principle of "exclusively defense-oriented"—that is, only conducting defensive counterattacks when subjected to armed attacks. However, the capability to attack enemy bases with long-range missiles clearly exceeds the boundaries of this traditional interpretation.

The institutional basis for this policy shift comes from the revised "National Security Strategy" and other "three security documents" passed in December 2022. These documents for the first time incorporated the "capability to attack enemy bases" (later renamed "counterstrike capability") into Japan's defense policy framework. Supporters argue that, in the face of North Korean nuclear missile threats and Chinese military modernization, Japan needs more effective deterrent measures. However, critics point out that this capability is inherently offensive and fundamentally conflicts with the spirit of the Constitution.

The public backlash against the deployment decision exceeded government expectations. On March 31, large-scale protests erupted outside the Kengun Garrison in Kumamoto Prefecture and the Fuji Garrison in Shizuoka Prefecture. Local residents' concerns focused on two main aspects: first, these garrisons are located in densely populated areas, with schools and hospitals nearby, and if they become targets of attack, it could result in severe civilian casualties; second, residents believe the government completely ignored local opinions, with even the local governor and mayor not being notified in advance, let alone holding any public briefings.

The criticism from Kenji Kido, a local community leader in Kumamoto, is quite representative: "The Ministry of Defense's actions will only deepen the distrust between the government and the public. Instead of spending money on weapons, it would be better to invest resources in peaceful diplomacy and friendly relations to maintain peace." At the protest site in Shizuoka, demonstrators chanted slogans such as "Do not deploy missiles in Fuji," "This violates Article 9 of the Constitution," and "The Self-Defense Forces must not become the vanguard of the United States," reflecting the public's deep concern about Japan being drawn into U.S.-led military actions.

Opposition parties expressed strong opposition to the deployment. Mizuho Fukushima, leader of the Social Democratic Party of Japan, stated bluntly: "Deploying missiles with the capability to attack enemy bases under the circumstances of having an exclusively defense-oriented policy and Article 9 of the Constitution is unconstitutional." Members of various opposition parties, including the Japanese Communist Party and the Senate faction "Okinawa no Kaze," participated in the protests. On April 1, six groups calling for the abolition of security laws and the restoration of constitutionalism held a press conference at the Senate members' office building, announcing the launch of a "petition campaign against amending Article 9 of the Constitution." The Japan Peace Committee also submitted a petition with approximately 57,000 signatures calling for a ban on arms exports to the Diet.

It is noteworthy that this deployment is closely related to the constitutional amendment agenda promoted by the administration of Sanae Takaichi. Critics point out that under Takaichi's administration, the process of amending Article 9 of the Constitution is accelerating. The Ryukyu Shimpo warned in an editorial that after the passage of the new "three security documents," Japan is rapidly shifting from a "country capable of waging war" to a "country wanting war." The editorial emphasized that the so-called "capability to attack enemy bases" is not true "deterrence" but rather a dangerous thing that continuously creates threats.

At the same time, on April 2, the Japanese Ministry of Defense announced another plan: to establish a "multi-layered" coastal defense system centered on drones. Defense Minister Shinjiro Koizumi stated at a Foreign Affairs and Defense Committee hearing that this is an important component of strengthening the foundation of national defense equipment. This plan indicates that Japan is systematically enhancing its military capabilities, not only limited to long-range strikes but also including the modernization of domestic defense.

From a regional security perspective, Japan's military transformation will inevitably affect the strategic balance in Northeast Asia. The Chinese Ministry of Foreign Affairs has expressed concern, pointing out that Japan's actions contradict its long-standing claim of an "exclusively defense-oriented" policy. South Korean public opinion is also vigilant, fearing that Japan's military expansion could undermine regional stability. More importantly, this deployment clearly demonstrates the trend of deepening integration of the Japan-U.S. alliance—the JSDF is gaining the capability to conduct "expeditionary" operations in coordination with the U.S. military.

This deployment of long-range missiles marks a historical turning point. The restraint-based security policy framework established by post-war Japan through Article 9 of the Constitution and the principle of "exclusively defense-oriented" is undergoing fundamental reconstruction. Although the government claims this is a necessary measure to respond to real threats, the strong backlash from civil society shows that this shift has not gained widespread social consensus. How Japan finds a balance between strengthening defense capabilities and maintaining the peace constitution will be a core issue in future political debates. For the Northeast Asian region, this shift in Japan's military policy undoubtedly adds new uncertainties to an already tense geopolitical situation.