Japan’s Ministry of Defense announced its Fiscal Year 2023 budget request on Dec. 23, and included in it were several new details about the island nation’s future ballistic missile defense, or BMD, warships. Tokyo plans to build two of these purpose-built vessels in place of its canceled Aegis Ashore BMD installations as a means to better defend against ballistic missiles — especially those from increasingly belligerent North Korea. Part of this release included the first official concept art showing what Japan is looking for in these vessels.
First reported by Naval News and then Sam LaGrone of USNI News, Japan’s Ministry of Defense (MoD) highlighted in its budget request the need for two such Aegis system-equipped vessels (ASEV) so that its current multi-role Aegis-equipped destroyers can be leveraged for different missions. The document also emphasized Japan’s prioritization of developing ships with the utility and capacity to address not only ballistic missile threats, but also those posed by hypersonic weapons.
Japan’s land-based Aegis Ashore concept, which included two installations, was its initial solution for more comprehensively defending against ballistic missiles, but the initiative was officially halted in 2020 due to budget issues, technical problems, and public outcry over the potential health impacts caused by its radar radiation. Instead, ASEV has been introduced as a more flexible and arguably survivable answer to Japan’s missile defense concerns without the hurdles brought on by static Aegis Ashore installations.
As for the future ASEVs’ metrics, details are still relatively sparse, and the MoD report did not include specific dimensions. However, The War Zone in the past has cited details provided by local Japanese news outlets that gave a general idea of the eventual size of these ships. For instance, The Nikkei reported that the ASEVs are expected to be around 690 feet long and have a beam of around 130 feet.
Other reports have suggested that the ASEVs will be more closely representative of Japan’s Maya class of Aegis destroyers. Compared to The Nikkei’s data on the ASEVs, Maya class destroyers are over 100 feet smaller in length, 57 feet slimmer in width, and have a displacement of 9,000 tons.
It is also worth mentioning that the first official rendering (the lead image for this article) bears a notable resemblance to the BMD ship concept for the U.S. Navy based on the LPD-17 San Antonio class Amphibious Transport Dock. The metrics that have been floated before also more align with a similar design to it than a destroyer. This would make sense for a BMD warship as its mission would essentially be sitting and scanning for incoming threats while armed with a large arsenal of weapons and an incredibly powerful radar. Speed would not be a priority, although long endurance, communications and command and control capabilities, sea-keeping abilities, weapons magazine capacity and adaptability, and reliability would be.
Regardless, ASEV is in its early stages of development, and requirements and operational needs are likely still being defined or at least refined. Its dimensions could very well change throughout this development process.
Currently, eight total ships comprise the Japan Maritime Self-Defense Force’s (JMSDF) Aegis fleet: two Maya class, two Atago class, and four Kongō class destroyers, all of which can be read about in this past War Zone piece. The Maya class ships, the youngest in the fleet, are subvariants of the Atago class, which itself is an evolution of the Kongō class vessels that are derived from the U.S. Navy's Arleigh Burke class.
According to Naval News, to free these ships up for other operations and realize the goals outlined in the MoD’s budget request, Japan will be designing its two future ASEVs with “SM-6 missiles from Raytheon, a ship-launched derivative of Type 12 surface-to-ship missile, and other undisclosed capabilities." This, however, does not make sense. First off, the SM-3 mid-course interceptor is Japan and the U.S. Navy's primary BMD weapon. Japan is even partnered with the U.S. directly on the SM-3 Block IIA program. Aegis Ashore and these vessels would be built around the SM-3 specifically.
SM-6 would make sense as it has anti-air and anti-ship capabilities for self-defense, but it also has terminal ballistic missile defense capabilities, as well. This would be especially important for countering direct anti-ship ballistic missile attacks on the ASEVs themselves, or swatting-down nearby ballistic missile attacks that get by the SM-3s. In addition, the SM-6 is the only weapon available that is capable, even to a highly limited degree, of intercepting some types of hypersonic weapons. You can read more about that here. As for addressing hypersonic weapons, the MoD document asserted that the ships should be developed with real estate that can be made available for hypersonic interceptors that are currently under development.
In other words, SM-3 is a critical component of this system and one that Japan is already highly invested in. The mention of anti-ship missiles is puzzling, but the vessels could accommodate standoff strike weapons that can be launched from its vertical launching system (VLS) cells.
The rendering shows the destroyer with 64 total VLS cells. Six sets of eight VLS cells can be seen on the ship’s front deck, with another four sets of eight above the helicopter hangar. This could be just a basic representation and not requirements specific, but it is clear that the ships would have a large magazine. This would give the ASEVs the advantage of dedicating all if not the vast majority of its magazine to BMD and hypersonic missile defense as opposed to Japan’s aforementioned Aegis destroyers whose cells are mostly packed with a large variety of weapons to cover their wide mission set.
One would imagine that Japan's BMD-capable destroyers could help with additional BMD coverage in a crisis or when an ASEV is offline and could do so in other regions as part of coalition operations, but these ASEVs would free them from the very resource-intensive homeland BMD mission on a daily basis.
Just like the Aegis-enabled ships in both Japan and the United States that have preceded them, the two forthcoming ASEVs will be built upon the existing Aegis Combat System (ACS). However, the MoD document outlined that Japan’s ASEVs will incorporate Lockheed Martin’s AN/SPY-7 active electronically scanned air search radar that was initially to be procured for the now-terminated Aegis Ashore effort.
According to Naval News, Lockheed Martin is dubbing the overall integration process behind getting SPY-7 onto the ASEVs as J7.B. This term identifies the initiative through which the company will incorporate SPY-7 into the latest software that is currently installed aboard Japan’s Aegis ships known as J7. J7.B was recently tested with the JMSDF, the Missile Defense Agency (MDA), and the U.S. Navy in September of this year to demonstrate how the ASEV’s BMD fire control loop would perform against ballistic missile threats with the help of SPY-7.
“MDA has confirmed Aegis Baseline J7.B hardware and software can command and control the SPY-7(V)1 radar, demonstrating all the major BMD capabilities required for the Japanese ASEV," said MDA Director, Vice Admiral Jon Hill. "This is another vital milestone in development and integration efforts. The overall ASEV J7.B with SPY-7 effort remains on track for meeting cost, schedule, and performance criteria. This program will provide Japan with the latest BMD capabilities, which will undoubtedly contribute to the defense of Japan under the increasing regional missile threats.”
The time required to fully flesh out the J7.B capability is expected to take up a decent chunk of the years leading up to the target commissioning for the pair of ASEVs. The MoD documents revealed that Japan hopes to have both of its new destroyers built by Fiscal Year 2027, which would fall anytime between April 2027 and March 2028.
USNI News reported that Japan’s budget request said the ASEVs will operate primarily in the Sea of Japan off the Korean peninsula. This area is becoming increasingly critical for Japan and its allies to maintain a presence as North Korea ramps up its ballistic missile activity and tensions with Russia and China grow.
All told, Japan is one step closer to laying the keel for its new Aegis-equipped destroyers, and the additional information provided by Japan’s MoD has it shaping up to be a flexible and valuable asset for the country’s future ballistic missile defense efforts.
Contact the author: Emma@thewarzone.com and Tyler@thedrive.com