Focus | Japan’s future ASEVs to surpass all modern destroyers as the most powerful class ever built.

At the International Defence Exhibition (IDEX) 2025 in Abu Dhabi, the US company Lockheed Martin exhibited a scale model of Japan’s Aegis System Equipped Vessel (ASEV), a new class of destroyer developed for ballistic missile defense (BMD) and integrated air and missile defense. As the largest destroyer of its kind, the ASEV is expected to measure 190 meters in length and 25 meters in width, with a standard displacement of 12,000 tons. The Japanese Ministry of Defense plans to construct two ships, scheduled for deployment as early as March 2028.
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The Aegis System Equipped Vessel (ASEV) class will remain larger than existing Japanese destroyers in terms of displacement, such as the latest Maya-class. (Picture source: Army Recognition)

The Aegis System Equipped Vessel (ASEV) program was initiated after Japan canceled the land-based Aegis Ashore system in June 2020 due to concerns over falling interceptor components and public opposition. In December 2020, the government announced that two Aegis-equipped vessels would be developed to maintain ballistic missile defense coverage while ensuring operational flexibility at sea. The ASEV program was designed to address evolving regional threats, particularly from North Korea and China.

Initially conceived as a dedicated ballistic missile defense (BMD) platform, the ASEV's design evolved to include additional offensive and defensive capabilities. By 2022, Japan’s Ministry of Defense revised the program to develop a multi-role destroyer capable of long-range strike missions and advanced missile defense. The 2024 Defense White Paper provided additional details on the ASEV, confirming its intended role in Japan’s missile defense strategy and its integration with the broader security framework. These modifications align with Japan’s updated National Security Strategy, which emphasizes enhanced deterrence and interoperability with allied forces.

The ASEV's development underwent significant modifications since its initial proposal. Early designs suggested a much larger vessel, exceeding 200 meters in length with a displacement of 22,000 tons. However, considerations related to cost, maneuverability, and operational integration resulted in a more compact design. Nevertheless, the ASEV will remain larger than existing Japanese destroyers in terms of displacement, such as the latest Maya-class.

Japan's Ministry of Defense has allocated substantial funding for the ASEV program, with the budget increasing beyond initial estimates. Originally, the cost for the two vessels was projected at approximately 392 billion yen ($2.63 billion) each, but rising material costs and currency fluctuations have raised the total projected cost to 783.9 billion yen ($5.25 billion). The fiscal year 2025 budget includes 86.5 billion yen ($579.55 million) for expenses related to various tests, including demonstration and live-fire tests, as well as radar integration. Additional funding is anticipated for continued construction and system enhancements.

Construction of the ASEV is assigned to two major Japanese shipbuilders. Mitsubishi Heavy Industries secured the contract for the first vessel in August 2024, while Japan Marine United Corporation was awarded the contract for the second in September 2024. The first ASEV is scheduled for commissioning in fiscal year 2027, with the second following in 2028. Once operational, these will be the largest surface combatants in Japan’s fleet since World War II. The ASEV will be operated by approximately 240 personnel, with accommodations designed for extended deployments, significantly enhancing Japan’s air and missile defense capabilities in the Indo-Pacific region.

The ASEV program was initiated after Japan canceled the land-based Aegis Ashore system in June 2020 due to concerns over falling interceptor components and public opposition. (Picture source: US DoD)

The two ASEVs will enable the Japan Maritime Self-Defense Force (JMSDF) to maintain continuous missile defense patrols without overburdening existing Aegis destroyers, allowing them to focus on broader maritime security operations. The JMSDF plans to integrate the ASEVs into a networked defense architecture, coordinating with both land-based and allied forces to provide comprehensive missile interception coverage against regional threats, particularly North Korea’s missile advancements.

The ASEV will be equipped with a radar array installation similar to the Spanish Álvaro de Bazán-class and the Australian Hobart-class, with the AN/SPY-7 AESA multifunction radar replacing the AN/SPY-1 system used on Japan’s existing Aegis destroyers. Developed by Lockheed Martin, the SPY-7 radar has five times the tracking capability of the existing SPY-1, according to the Japanese Ministry of Defense, and is capable of handling multiple simultaneous ballistic missile threats. The ASEV will also feature three AN/SPG-62 X-band radar illuminators, like previous Japanese Aegis destroyers, to provide guidance for air defense missiles using semi-active radar homing. Additionally, the AN/SPQ-9B radar will enable scanning for low-flying anti-ship cruise missiles (ASCMs), surface threats, and slow-moving aerial targets such as drones and helicopters.

To improve survivability, the ASEV is expected to integrate the Surface Electronic Warfare Improvement Program (SEWIP) Block 2 AN/SLQ-32(V)6 modules, making it the first Japanese destroyer to incorporate this system. It will also feature the NOLQ-2 ECM intercept and jammer and four Mk 137 chaff and decoy launchers, enhancing its electronic warfare capabilities by detecting and countering electronic threats. The radar and sensor suite is designed for long-range target acquisition, contributing to Japan’s broader missile defense network and interoperability with allied forces.

The ASEV's armament configuration makes it one of the most heavily armed destroyers globally. The vessel will feature 64 vertical launch system (VLS) cells at the bow and another 64 at the stern, totaling 128 cells—matching the highest number of VLS cells found on any existing destroyer, alongside South Korea’s Sejong the Great-class. These launchers will carry SM-3 and SM-6 surface-to-air missiles for defense against ballistic and hypersonic threats. The ASEV will also be equipped with Glide Phase Interceptors (GPI), a system under development to counter hypersonic weapons and cruise missiles.

The ASEV's armament configuration makes it one of the most heavily armed destroyers globally, and will include armements such as two sets of quadruple Type 12 anti-ship missile launchers positioned between the chimneys. (Picture source: MHI)

For offensive capabilities, the Aegis System Equipped Vessel (ASEV) will be armed with a Tomahawk Weapon Control System (TWCS) to operate Tomahawk cruise missiles, allowing for long-range land attacks. It will also carry two sets of quadruple Type 12 anti-ship missile launchers positioned between the chimneys. To reduce radar cross-section (RCS) and enhance stealth characteristics, these launchers are partially enclosed within the ship’s structure, with only the upper section exposed for missile deployment. A Mk45 Mod 4 127mm (5-inch) naval gun at the bow provides additional firepower for surface engagements and shore bombardment.

Additional armament includes two small gun turrets amidships, likely Mk46 30mm Gun Weapon Systems (GWS) for close-range defense, and two Phalanx Block 1B Close-In Weapon Systems (CIWS) positioned near the bridge and above the helicopter hangar. The ASEV will feature a twin helicopter hangar designed to accommodate two SH-60 helicopters for anti-submarine warfare (ASW) and surveillance operations. Its ASW capabilities will be further enhanced by two triple short-range torpedo tubes, possibly the Mk.32, and a hull-mounted sonar system. The vessel is also expected to integrate next-generation systems such as a high-power laser for countering drone saturation attacks, scheduled for introduction after 2032.

Most modern destroyers, including the Arleigh Burke and Type 055, use gas turbines in a combined diesel and gas (CODAG) or combined gas turbine and gas turbine (COGAG) arrangement, such as the South Korean Jeongjo the Great-class. The ASEV will employ a COGLAG (Combined Gas turbine-electric and Gas turbine) propulsion system, integrating two Rolls-Royce MT30 gas turbines with electric motors to enhance fuel efficiency for extended deployments and reduce operational costs. This hybrid system generates approximately 100,000 horsepower, allowing the vessel to reach speeds of around 30 knots. This system, paired with its advanced radar and missile suite, positions the ASEV as one of the most specialized ballistic missile defense platforms in service while retaining multi-role combat capabilities, as the vessel’s design includes provisions for future upgrades in weaponry and electronic warfare systems.

Compared to other destroyers such as the Russian Severomorsk, the ASEV stands out as one of the largest and most capable ships in its category. The Japan Maritime Self-Defense Force’s Maya-class destroyers, the latest Aegis-equipped ships before the ASEV, measure 170 meters in length, 21 meters in width, and have a displacement of 8,200 tons. The ASEV is significantly larger in all dimensions, with a 12,000-ton displacement and a length of 190 meters. In contrast, the U.S. Navy's Arleigh Burke-class Flight III destroyers, which serve as a benchmark for modern multi-role destroyers, measure 155 meters in length, with a displacement of 9,700 tons. The ASEV, at 190 meters in length and 12,000 tons in displacement, is larger than Japan’s Maya-class and the U.S. Arleigh Burke-class Flight III destroyers but smaller in displacement than the Zumwalt-class, which, despite sharing the same length, has a full-load displacement of 15,995 tons.

Among global counterparts, the Chinese Navy’s Type 055 Renhai-class cruiser is one of the few comparable ships, with a length of 180 meters and a displacement of approximately 13,000 tons at full load. While the Renhai-class features 112 vertical launch system (VLS) cells, the ASEV exceeds this with 128 VLS cells, placing it among the most heavily armed destroyers in service. The South Korean Navy’s Sejong the Great-class destroyers, at 165 meters in length and a displacement of 10,000 tons, also have 128 VLS cells, making them similar in firepower to the ASEV but smaller in size. Unlike most of these platforms, the ASEV prioritizes ballistic missile defense (BMD) as its primary role, incorporating the AN/SPY-7 radar, which Lockheed Martin states provides superior tracking performance compared to the AN/SPY-1 and AN/SPY-6 systems used by other Aegis-equipped ships.