Japan Signs Contracts to Build Two Advanced Aegis System Ships with Mitsubishi and JMU

Japan’s Ministry of Defense (MoD) has officially inked contracts with two of the country’s largest shipbuilders, Mitsubishi Heavy Industries (MHI) and Japan Marine United (JMU), to construct two Advanced Aegis-equipped ships (ASEVs). These highly advanced vessels are designed to enhance Japan’s missile defense capabilities and are scheduled to be delivered by fiscal years 2027 and 2028.

The contract with MHI, signed on August 23, 2024, is valued at approximately 139.7 billion yen ($980 million). JMU followed with a contract on September 18 for 132.4 billion yen ($930 million). According to Japan’s Acquisition, Technology, and Logistics Agency (ATLA), the price difference between the two contracts is due to differences in specific parts being procured, not a variation in overall specifications or performance between the ships.

ASEVs: Japan’s Floating Missile Defense Network

The ASEVs are part of Japan’s broader strategy to replace the Aegis Ashore system, a land-based missile defense program that was scrapped in 2020. The cancellation led the government to shift focus toward the development of mobile maritime platforms capable of intercepting ballistic missiles. These new ships are a critical part of Japan's commitment to bolstering its defenses in the face of growing regional threats from North Korea and China.

At the heart of these vessels will be Lockheed Martin's SPY-7 radar, one of the world’s most advanced multi-function radars. Designed to track and intercept ballistic missiles, the SPY-7 radar has scalability and high-performance features that make it a perfect fit for Japan’s maritime defense strategy. The ASEVs will be equipped to monitor the skies for missile threats and integrate with Japan’s broader defense network to ensure a robust and coordinated response to potential missile launches.

Why SPY-7 Matters

Lockheed Martin has been a key partner for Japan’s defense, particularly when it comes to Aegis-equipped systems. On September 10, 2024, Lockheed Martin hosted four Japanese journalists at its Rotary and Mission Systems (RMS) division in Moorestown, New Jersey, where the SPY-7 radar is developed and produced. This visit served to underscore the progress of the ASEV program, while also promoting the adoption of the SPY-7 radar on future vessels.

There is increasing competition between Lockheed Martin’s SPY-7 radar and Raytheon’s SPY-6 system, which is being widely adopted by the U.S. Navy. While both radar systems offer advanced capabilities, Lockheed Martin has been keen to highlight the SPY-7's flexibility, especially for Japan’s evolving defense needs. 

With Japan looking to retire its aging fleet of Kongo-class Aegis destroyers, which are nearing the end of their operational lifespan, the competition for the next-generation radar system is heating up. Mitsubishi Electric, for example, has already secured a contract to supply key components for the SPY-6, which may give Raytheon an advantage in future procurement rounds.

However, Lockheed Martin remains confident in the SPY-7’s interoperability with other Aegis systems, including those equipped with SPY-6, and continues to actively pursue contracts within Japan’s defense sector. The company has even opened discussions about local production and sustainment of SPY-7 radars, hinting that Japanese industry could be brought into the production fold.

Advanced Defense Systems: The Future of ASEVs

In addition to the SPY-7 radar, the ASEVs will be outfitted with cutting-edge defense technologies. One of the most talked-about systems is the Vertical Launch System (VLS) Mk.70 Payload Delivery System (PDS), which allows for the integration of various missile types, including the PAC-3 Missile Segment Enhancement (MSE). This missile, an improved version of the Patriot missile, can intercept both cruise and ballistic missiles, significantly expanding the ASEV’s defense capabilities.

The Mk.70 system’s container-based design provides flexibility in missile deployment and enhances the ship’s ability to respond to multiple types of threats. Japan has already deployed the PAC-3 MSE on land-based systems, and its integration into the maritime Aegis system marks an important step in expanding Japan’s layered missile defense network.

Lockheed Martin has successfully tested the PAC-3 MSE in the U.S., where it intercepted a cruise missile using a virtualized Aegis weapon system during trials at the White Sands Missile Range in New Mexico. These successful tests suggest that the ASEVs will offer a formidable defense against missile threats, both for Japan and as part of broader regional security efforts.

Japan’s Future Naval Fleet

Japan’s investment in the ASEV program is part of a larger shift in its naval strategy. In December 2022, the Japanese Cabinet approved a Defense Buildup Program that calls for a total of 10 Aegis-equipped ships, adding two new vessels to the existing fleet of eight. The current fleet includes four Kongo-class, two Atago-class, and two Maya-class destroyers. With the Kongo-class approaching the end of its service life, Japan is looking to not only replace these ships but also enhance its naval capabilities.

The commissioning of the ASEVs in 2027 and 2028 will play a pivotal role in Japan’s defense. As the global security environment continues to evolve, Japan is ensuring its naval fleet remains at the forefront of missile defense technology.

The question remains whether future ships will also adopt Lockheed Martin’s SPY-7 radar, or if the U.S.-developed SPY-6 will gain favor due to its broader deployment within the U.S. Navy. Regardless of the final decision, Japan’s partnership with U.S. defense companies, including Lockheed Martin and Raytheon, underscores the importance of international collaboration in modern naval warfare.

With state-of-the-art technology and flexible capabilities, the ASEVs are poised to become a critical part of Japan’s defense strategy for years to come.