Japan lays keel of both ASEV Missile Defense Ships
Japan’s Ministry of Defense has confirmed that both Aegis System Equipped Vessels (ASEV) planned for the Japan Maritime Self-Defense Force (JMSDF) have already been laid down, marking the start of full-scale construction of the two-ship missile defense program. The JMSDF plans to operate two ASEV sh
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Japan’s Ministry of Defense has confirmed that both Aegis System Equipped Vessels (ASEV) planned for the Japan Maritime Self-Defense Force (JMSDF) have already been laid down, marking the start of full-scale construction of the two-ship missile defense program.
The JMSDF plans to operate two ASEV ships as part of Japan’s ballistic missile defense (BMD) architecture. The first vessel was laid down on July 18, 2025, at Mitsubishi Heavy Industries’ Nagasaki shipyard on Kyushu Island. The second ship followed on February 5, 2026, at Japan Marine United’s Isogo shipyard in Yokohama City, south of Tokyo. The milestone confirms that construction of both ships has entered the main production phase.
According to the Ministry of Defense, the first ship is scheduled to be launched in fiscal year 2026 and commissioned in March 2028. The second ship will follow roughly one year later, with launch planned in FY2027 and delivery to the JMSDF in March 2029.
Both vessels are expected to become core platforms of Japan’s ballistic missile defense system.
Replacement for Cancelled Aegis Ashore
The ASEV program was initiated after Japan cancelled the Aegis Ashore land-based missile defense system in 2020.
Instead of fixed land installations, the government opted for large sea-based BMD platforms capable of persistent operations at sea. The Ministry of Defense plans to operate the two ships in a configuration that allows continuous missile surveillance coverage over the entire Japanese archipelago.
The vessels are designed as dedicated ballistic missile defense ships, intended to maintain long-duration tracking and warning missions.
A key objective of the program is also operational: to relieve the JMSDF’s eight existing Aegis destroyers of the heavy burden of continuous BMD patrols.
For years, Japan’s Aegis destroyers have frequently been tied to ballistic missile monitoring missions due to North Korea’s frequent missile launches. This has limited their availability for other roles such as:
Fleet air defense
Anti-submarine warfare
Joint operations with U.S. forces
Indo-Pacific presence missions
By assigning persistent BMD duties to the ASEV ships, the JMSDF aims to return existing Aegis destroyers to broader multi-mission operations.
The Aegis System Equipped Vessel (ASEV) under construction seen on February 9 at MHI’s Nagasaki Shipyard & Machinery Works in Japan. (Photo credit: Ryo Eto)
Large Hull Designed for Persistent Missile Defense
According to the Ministry of Defense, each ASEV ship will measure about 190 meters in length, with a beam of about 25 meters and a standard displacement of roughly 12,000 tons.
The vessels will be equipped with the AN/SPY-7 radar, a large fixed-array radar consisting of four antenna faces, each approximately 14 feet (about 4.3 meters) high.
Japanese officials say the SPY-7 radar offers roughly five times the tracking capability of the SPY-1 radar currently installed on the JMSDF’s eight Aegis destroyers.
The radar is expected to improve the ability to detect and track:
The ships’ large hull design is intended to improve stability in heavy seas, allowing the vessels to maintain long-duration ballistic missile surveillance and tracking missions.
Procurement costs are estimated at approximately 392 billion yen (about $2.5 billion) per ship.
ASEV rendering. Lockheed Martin image.
128-Cell VLS and Advanced Missile Defense
The ASEV ships will be equipped with the latest Aegis combat system paired with the SPY-7 radar.
Each vessel will feature a 128-cell Vertical Launch System (VLS)—significantly more than the 96 cells installed on Japan’s latest Aegis destroyers.
The VLS will be capable of launching:
SM-3 Block IIA interceptors, jointly developed by Japan and the United States for ballistic missile defense
SM-6 missiles, capable of engaging advanced aerial threats, including hypersonic glide vehicles
The ships will also support Japan’s emerging counterstrike capability.
Planned armament includes:
the extended-range Type 12 anti-ship missile (ship-launched improved variant)
the U.S.-made Tomahawk cruise missile
The vessels are also expected to accommodate the future Glide Phase Interceptor (GPI) designed to counter advanced missile threats, including hypersonic weapons.
Japanese officials have also highlighted the ships’ growth margin, noting that the large hull design could allow the future integration of additional systems, such as high-energy laser weapons for counter-drone defense.
The scale model of the JMSDF’s future AEGIS System Equipped Vessel (ASEV) — an exceptionally large stealth guided-missile destroyer, surpassed in size only by the US Navy’s unique Zumwalt-class.
A New “Cruiser” for the JMSDF
Unlike existing JMSDF Aegis destroyers, which carry the hull classification DDG, the ASEV ships are expected to receive the designation CG (guided missile cruiser).
At 190 meters in length and about 12,000 tons standard displacement, the ships will be significantly larger than the U.S. Navy’s Arleigh Burke Flight III destroyers.
Although the Ministry of Defense has not disclosed the full-load displacement, defense analysts estimate the ships could reach around 16,000 tons, potentially exceeding the size of the U.S. Navy’s Zumwalt-class destroyers and China’s Type 055 destroyers.
Excluding aircraft carriers and Russia’s Kirov-class nuclear-powered battlecruisers, the ASEV could become one of the largest surface combatants in the Western world once commissioned.
