North Korea's Missile Resumption and Japan'

📡 THE SIGNAL — What Happened

Why it matters: North Korea's resumption of ballistic missile launches is becoming a turning point that shakes the foundation of Japan's post-war defense policy. The shift from an exclusively defensive posture (Senshu Bōei) to possessing counterstrike capabilities could irreversibly alter the security architecture of East Asia.

• Military — North Korea resumed ballistic missile launches in early 2026, conducting multiple launches towards the Sea of Japan (East Sea).
• Military — The missiles launched included intermediate-range ballistic missile (IRBM) and intercontinental ballistic missile (ICBM) class, confirming technological advancements.
• Defense Policy — The Japanese government officially announced its stance to consider strengthening its interception systems and enhancing its own deterrence capabilities.
• Defense Budget — Japan's defense spending has surged since fiscal year 2023 towards the goal of 2% of GDP, with the fiscal year 2026 budget expected to reach approximately 8 trillion yen.
• Equipment — Japan has agreed with the United States to acquire Tomahawk cruise missiles and has begun sequential deployment from fiscal year 2025.
• Diplomacy — Security cooperation among Japan, the U.S., and South Korea has deepened since the Camp David Agreement (August 2023), but South Korea's domestic political instability casts a shadow over the sustainability of cooperation.
• Technology — North Korea has succeeded in developing solid-fuel propulsion technology, increasing the difficulty of detection and interception due to reduced launch preparation time.
• Economy — A portion of North Korea's nuclear and missile development funds is estimated to come from cryptocurrency theft and cybercrime proceeds, amounting to several hundred million dollars annually according to UN reports.
• International — Additional sanction resolutions at the UN Security Council remain virtually impossible due to vetoes by China and Russia.
• Regional — Construction of Japan's Aegis System Equipped Vessels (Aegis Ashore alternative) is underway, aiming for commissioning in fiscal year 2027.
• Politics — In Japan, debates over the constitutional interpretation regarding the possession of counterstrike capabilities have reignited, with differing views between ruling and opposition parties.
• Alliance — The United States is advancing the reorganization of U.S. forces in Japan and a review of command and control structures, strengthening its stance to encourage Japan's enhancement of its independent defense capabilities.

To understand North Korea's resumption of missile launches and Japan's defense policy transformation, it is necessary to trace the structural changes in the post-war East Asian security order.

After its defeat in 1945, Japan adopted "exclusive defense" (Senshu Bōei) as its national policy under Article 9 of its pacifist constitution, entrusting the core of its security to the U.S. "nuclear umbrella" and the Japan-U.S. Security Treaty. This structure functioned throughout the Cold War, allowing Japan to concentrate resources on economic growth. However, this path, also known as the "Yoshida Doctrine," harbored a structural weakness: its vulnerability to fundamental changes in the security environment.

The first turning point was North Korea's Nodong missile launch test in 1993. This missile, which landed in the Sea of Japan, confronted Japan with the reality that its mainland was exposed to a direct ballistic missile threat. Triggered by this, Japan decided to introduce a ballistic missile defense (BMD) system and proceeded with the deployment of PAC-3 and Aegis BMD. However, at this stage, it remained limited to strengthening the "shield" and did not venture into possessing the "spear."

The second turning point was North Korea's repeated nuclear tests since 2006. Through a total of six nuclear tests in 2006, 2009, 2013, 2016 (twice), and 2017, North Korea became a de facto nuclear-weapon state. In particular, the 2017 hydrogen bomb test and the launch of the ICBM-class "Hwasong-15" demonstrated that North Korea was acquiring the capability to directly threaten the U.S. mainland, posing a fundamental question to Japan: "Will the U.S. nuclear umbrella truly function?"

The third turning point was the three security-related documents—the "National Security Strategy," "National Defense Strategy," and "Defense Buildup Program"—approved by the Cabinet in December 2022. Here, Japan explicitly stated for the first time its possession of "counterstrike capabilities" (formerly "enemy base attack capabilities"). This was a groundbreaking policy shift, maintaining the framework of exclusive defense while possessing the ability to attack an adversary's missile launch sites and other targets. The agreement to acquire Tomahawk cruise missiles and the accelerated development of indigenous stand-off missiles are concrete manifestations of this.

However, why is a further transformation being discussed "now," at this particular timing? Multiple structural factors are intertwined in the background.

First, there is a qualitative change in North Korea's missile technology. The successful development of solid-fuel propulsion rockets, experiments with hypersonic glide vehicles (HGVs), and the improvement of submarine-launched ballistic missile (SLBM) capabilities cast doubt on the effectiveness of Japan's existing BMD systems. The recognition that interception alone is insufficient to cope is spreading within defense authorities.

Second, there is the multipolarization of the international order and the uncertainty of U.S. involvement. The prolonged war in Ukraine, tensions in cross-strait relations, and instability in the Middle East have forced the U.S. to disperse its security resources. The re-emergence of the Trump administration (January 2025) will further intensify demands for burden-sharing from allies, increasing pressure on Japan to enhance its independent defense capabilities.

Third, there is China's rapid military expansion. The U.S. Department of Defense estimates that China's nuclear warhead count will exceed 1,000 by 2030, and its conventional forces, particularly naval and air power, are also remarkably increasing. For Japan, the North Korean missile threat is situated within the broader context of China's military rise. The development of counterstrike capabilities is significant not only for deterrence against North Korea but also against China.

Fourth, there is political instability in South Korea. Since the martial law turmoil at the end of 2024, South Korea's domestic politics have remained chaotic, increasing uncertainty about the sustainability of trilateral cooperation among Japan, the U.S., and South Korea. Japan, therefore, faces a growing need to secure its own deterrence capabilities under circumstances where it cannot overly rely on cooperation with South Korea.

The accumulation of these structural changes is accelerating a fundamental transformation of Japan's defense policy, which has been maintained for 80 years since the end of the war. North Korea's resumption of missile launches is a "catalyst" in this long-term trend, not merely a temporary crisis, but a mirror reflecting the structural changes in the East Asian security order.

The delta: North Korea's resumption of missile launches is not merely a repetition of provocations, but a catalyst for an irreversible structural shift in Japan's security, moving from a "exclusively defensive and U.S.-dependent" model, maintained for 80 years since the war, to one of "possessing independent deterrence capabilities." What has changed is not just the number of missiles, but Japan's cognitive framework towards its own security.