The Japan Maritime Self-Defense Force (JMSDF) plans to procure two ASEVs, which are alternatives to Japan’s now-defunct land-based Aegis Ashore ballistic missile defense (BMD) system. The first ASEV is scheduled to be commissioned by the end of March 2028, and the second by the end of March 2029.
The newest image released in the 2024 defense white paper, published on July 12, 2024, shows the continuing progress in detailed design of the ASEV.
For one thing, apparently, the design of the bridge structure follows the Maya-class Aegis destroyer, but the window shape on the bridge is horizontal like the Mogami-class frigate, also known as FFM, which is designed to improve visibility while also accommodating a smaller number of bridge staff due to manpower reduction.
The configuration of the main armament used by the ASEV also appears similar to that of the Maya-class, including a Mk-45 (Mod.4) 5-inch/62-caliber (127mm) main gun.
It remains to be seen whether the ASEV will be installed with equipment similar to the OAX-3 electro-optical and infrared (EO/IR) sensor system, installed on the FFM, to improve all-round surveillance and vigilance.
A Japanese naval expert familiar with the design of world warships told Naval News on the condition of anonymity that it appears that aerials and other equipment are concentrated on the protrusion around the outer periphery of the first funnel.
“I wondered if there would be any issues with heat caused by the main engine’s exhaust smoke or the effects of radio interference in that area,” the expert pointed out, adding “This is the first time I’ve seen this type of outfitting, so it’s interesting.”
The expert also focused on about the structures of the first and second funnels.
“On a conventional ship, SSMs would be installed there. The reason some structure is placed in the area that will become the deck working passage may be to allow for extra space in the future to accommodate additional long-range missiles, etc.,” the expert said.
A former JMSDF officer also told Naval News on condition of anonymity that the ASEV is still in the design stage, and expects details will continue to be changed depending on the design.
“In the future, like the Mogami-class frigate, the hull will be equipped with more hatches on the sides to hide equipment and improve its stealth capabilities,” the former officer said.
ASEV weapon and sensor systems
The two ASEVs are set to be fitted with the Lockheed Martin SPY-7, originally procured for Aegis Ashore, and the version of the Aegis system is the J7.B, which has been modified to integrate the SPY-7 into Baseline 9 (BL9).
On April 4, 2024, Lockheed Martin announced it had successfully demonstrated the first live track AN/SPY-7(V)1 radar, or the SPY-7, for the ASEV.
The MoD said in the latest white paper that the SPY-7 has five times the tracking capability of the SPY-1 and can deal with missiles launched on lofted trajectories and multiple ballistic missiles fired simultaneously.
The ASEV vessels will feature an impressive 128 Vertical Launch System (VLS) cells. This is more than the Maya-class destroyer’s 96 cells of Mk41 VLS (64 cells forward and 32 cells aft).
The MoD explains that the ASEV’s VLS will be given expandability to accommodate future equipment to deal with Hypersonic Glide Vehicles (HGVs) during the gliding phase.
Other weapon systems of the ASEV include:
- SM-6 also known as RIM-174 Standard Extended Range Active Missile (ERAM)
- SM-3 Block IIIA Surface to Air Missiles
- Cooperative Engagement Capability (CEC) that enables the vessels to remotely fire anti-aircraft targets tracked by other ships and so on.
Equipment planned for installation after 2023 (expandability/future growth):
- The upgraded Type 12 SSM to deal with enemy fleets from outside their threat range in surface warfare
- Tomahawk missiles to deal with ground forces from outside the enemy’s threat range in island defense
- High-power lasers, etc. to dealing with drone saturation attacks
The MoD has begun construction of two ASEV from this fiscal year 2024. It has allocated 373.1 billion yen ($2.3 billion) in this fiscal year’s budget for acquisition costs, including construction costs. In addition, it has secured 81.5 billion yen($504 million) for related expenses such as various test preparations and operational support facilities such as test sites. So in total, a whopping 454.6 billion yen ($2.81 billion) has been allocated for the expenses of the ASEVs in the fiscal year 2024 alone.
According to the MoD, the size of the ASEV is 190 meters in length, 25 meters in width, and a standard displacement of 12,000 tons. In comparison, the JMSDF’s latest Aegis ship, the Maya-class, is 170 meters in length, 21 meters in width, and has a standard displacement of 8,200 tons. The ASEV is also 1.7 times larger than the U.S. Navy’s latest Aegis ship, the Arleigh Burke Flight III, in tons.
The MoD stresses the ASEV will have capabilities equal to or greater than those of the most advanced Aegis ships.
