From "Defensive Defense" to "Proactive Deterrence": Japan's Major Shift in Security Policy Redraws the Strategic Map of Northeast Asia

In April 2026, Japan's security policy reached a historic turning point. The cabinet led by Sanae Takaichi abolished the operational guidelines of the "Three Principles on Transfer of Defense Equipment," which had been in place for nearly 80 years since the end of World War II, effectively lifting the ban on the export of lethal weapons. This is not merely a policy adjustment; it is a clear declaration that Japan is breaking out of its "defensive defense" shell and steering towards "proactive deterrence." This decision holds profound significance in the strategic environment of Northeast Asia, where the intersection of China's maritime expansion, North Korea's nuclear and missile threats, and the pressure from the United States to reassess its alliance structure is evident.

The core of this relaxation of export regulations lies in the expansion of the export targets for defense equipment, which had previously been limited to five categories: rescue, transport, alert, surveillance, and mine sweeping, to nearly all areas, including lethal weapons. According to data from SIPRI (Stockholm International Peace Research Institute), Japan's arms exports accounted for only 0.1 percent of the global total as of 2024. However, if defense companies like Mitsubishi Heavy Industries and Toshiba fully enter overseas markets, this figure could change rapidly. In fact, Australia has already signed contracts with Mitsubishi for the purchase of three Mogami-class frigates and the joint production of an additional eight, while the Philippines has shown strong interest in acquiring used frigates from Japan. A senior Polish government official also expressed hope that "Japan's participation could alleviate some of the bottlenecks in the defense supply chain."

The backdrop to this policy shift is the rapid expansion of the Chinese Navy. The Japan Maritime Self-Defense Force's monitoring operations in surrounding waters have been increasing year by year, necessitating the mobilization of not only conventional escort ships but also missile boats, supply ships, and even mine sweepers. This over-deployment has strained training opportunities and adversely affected the overall readiness of the forces. To address this issue, the Japan Maritime Self-Defense Force implemented a large-scale organizational reform at the end of March 2026, establishing a new "Patrol Defense Group" in Yokosuka. This specialized unit is tasked with deploying five patrol defense teams across bases nationwide, concentrating Mogami-class frigates (FFM) and Hayabusa-class missile boats.

The Mogami-class frigate is a state-of-the-art stealth frigate measuring 133 meters in length and displacing approximately 5,500 tons, equipped with a Mk45 5-inch gun, anti-ship missiles, and the SeaRAM close-in defense system. Currently, the seventh ship and beyond are being equipped with a 16-cell Mk41 vertical launch system (VLS), enabling the operation of the Type 07 vertical launch ASROC (VLA). With the deployment to the Patrol Defense Group, these vessels will specialize in peacetime monitoring and patrol missions, allowing the main fleet of escort ships to focus on their original wartime missions and practical training.

Another noteworthy development is the "Sakura-class" patrol vessel (OPV), scheduled to enter service in 2027. This new vessel boasts a standard displacement of approximately 1,900 tons, a length of 95 meters, and a maximum speed of about 25 knots, and can be operated with a very small crew of around 30 personnel, utilizing advanced bridge systems that apply automation technologies from civilian shipping. The construction cost is also kept low at about 6 billion yen (approximately 40 million dollars) per ship, with a total budget of about 35.7 billion yen for the first four ships. Armament is limited to a single 30mm machine gun, but plans are in place to later equip it with the V-BAT vertical takeoff and landing unmanned aerial vehicle system from Shield AI, significantly enhancing its wide-area maritime surveillance capabilities. Additionally, the future installation of electronic intelligence (ELINT) equipment is planned, allowing it to function as an information-gathering platform that goes beyond mere "visual monitoring."

Looking at the overall picture of security policy, the recent lifting of export restrictions is just the tip of the iceberg. Prime Minister Takaichi has publicly stated in a parliamentary speech in October 2025 that the three security documents—National Security Strategy (NSS), National Defense Strategy (NDS), and Defense Build-Up Program (DBP)—will be revised within the year. The first expert meeting held on April 27 included 15 specialists, such as former U.S. Ambassador Kenichiro Sasae and former Defense Vice Minister Tetsuro Kuroe, who discussed responses to new forms of warfare and the construction of sustainable combat capabilities. The defense budget for fiscal year 2026 is expected to reach approximately 61 billion dollars, with about 6 billion yen allocated for AI-related projects. Special funding has been earmarked for coastal unmanned defense systems, cooperative unmanned aerial vehicles, and drone swarm control.

The movement towards Japan-South Korea cooperation is also accelerating. The defense minister plans to visit South Korea in June, and a deputy-level "2+2" meeting is scheduled to be held in early May. In January 2026, the Japan Air Self-Defense Force provided air-to-air refueling support to South Korean military aircraft, and during the visit of the U.S. Secretary of the Navy in April 2026, the expansion of cooperation with major Japanese shipyards was confirmed. In the context of the realignment of U.S. forces in Japan, plans are also taking shape to utilize Japanese shipbuilding technology in the revitalization of the U.S. shipbuilding industry.

However, this rapid transformation faces numerous challenges both domestically and internationally. Within Japan, discussions including the revision of Article 9 of the Constitution remain divisive, and there is strong public resistance rooted in a tradition of pacifism. In South Korea, skepticism towards military cooperation remains significant due to historical conflicts stemming from Japan's colonial rule. Furthermore, Japan's defense industrial base is constrained in terms of production capacity, and it does not have a system in place to immediately handle large orders. Continuous investment in expanding production lines, human resource development, and technological innovation in defense companies is essential.

Nevertheless, the direction of this series of changes is clear. Japan is attempting to break away from the post-World War II "defensive defense" paradigm and establish itself as a core supplier of defense equipment within the alliance network. As the Ukrainian ambassador to Japan stated to Reuters, this relaxation of export regulations "opens the door to future military equipment provision from Japan," indicating that the ripple effects of this decision could extend beyond Northeast Asia and influence the global security environment.

On March 31, 2026, the deployment of the Type 25 surface-to-ship guided missile (SSM) with a range of 1,000 kilometers and the Type 25 high-altitude pressure guided missile (HVGP) with a range of several hundred kilometers began. The realization of these "counterstrike capabilities" symbolizes Japan's transformation from a mere "shield" to a nation equipped with both "spear and shield." The security environment in Northeast Asia is indeed in the midst of a historic reconstruction.