Japan’s latest Defense White Paper unveils a new image of the Aegis system equipped vessel (ASEV)
The JMSDF plans to procure two ASEVs, which are alternatives to Japan’s now-defunct land-based Aegis Ashore ballistic missile defense (BMD) system.
The newest image released in the defense white paper shows the configuration of the main armament used by the ASEV is similar to that of two Maya-class Aegis-equipped destroyers, including a Mk-45 (Mod.4) 5-inch/62-caliber (127mm) main gun.
However, a former JMSDF officer told Naval News on condition of anonymity that the topside area above the bridge of the ASEV looks closer to that of Australia’s Hobart-class Aegis-equipped air warfare destroyers, with both the ASEV and the Hobart-class destroyer equipping their topsides with Aegis radar arrays.
The ASEV is 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). Meanwhile, the Maya-class destroyers are equipped with the Aegis Baseline J7 BMD-capable weapon system supported by the Lockheed Martin/Raytheon AN/SPY-1D(V) phased array radar. Asked about the ASEV’s specifications such as its displacement and length, a defense official in charge of a press briefing about the defense white paper told Naval News on July 26:
“Regarding the Aegis system equipped vessel, we have put a new image based on the latest design status in this year’s white paper. However, I have no idea of any further details. Right now, I think that the work is proceeding toward the budget request for the next fiscal year 2024. I have no answers at this time.”
One military expert in Japan told Naval News the ASEV mast configuration appears similar to Spain’s F110-class frigate, also known as the Bonifaz-class. “Since the F110-class frigate will be fitted with almost the same SPY-7 system as the ASEV, a decision may have been made to avoid technical adventures as it is difficult to refer to the SPY-1 family of US ships,” this expert said.
As Naval News reported in June 2023, the Japanese news agency Jiji Press said 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). This would provide the ASEV with improved interception capabilities against not only conventional ballistic missile warheads but also hypersonic glide vehicles (HGVs).
Around August 2022, the ASEV was once dubbed by critics as the “Yamato of Reiwa,” the biggest Japanese warships since World War II, when the defense ministry explained at its budget request for FY2023 that the new ships will be 210 meters or less long, 40 meters or less wide, and have a standard displacement of 20,000 tons. In comparison, the two Izumo-class helicopter carriers, currently the biggest ships in the JMSDF, are 248 meters long, 38 meters wide, and have a standard displacement of 19,500 tons.
However, this plan provoked controversy as those new ships could place yet another heavy burden on the JMSDF and taxpayers. In addition, military experts said the ships are too large and lack maneuverability.
In response to such criticism, the defense ministry has revised the ship’s construction plan and has been considering making it smaller.
A defense official told Naval News in December 2022 as follows.
“Regarding the Aegis-equipped ship, we are considering making it smaller than the size in the budget request for FY2023 last summer. For example, we are considering adding sonar as an anti-submarine capability for dealing with submarines. However, the basic mission of the new ships is BMD. In that sense, we are currently considering it with the image that it will be a little closer to our current Aegis ships.”
According to an article published by the Asahi Shimbun on November 18, 2022, the ASEV is expected to still be larger than the Maya-class, the largest Aegis destroyer of the JMSDF (standard displacement of 8,200 tons, length of 170 meters, width of 21 meters).
In 2023 the defense ministry allocated 220.8 billion yen ($1.58 billion) to procure two additional ASEVs with SM-3 Block IIA and SM-6 missiles. Procurement of the latter two capabilities has been allocated 59.5 billion yen and 13.6 billion yen, respectively.
In April, the Japanese government awarded contracts to two local companies to design the ASEVs. Mitsubishi Heavy Industries (MHI) was awarded a 1.7 billion yen contract while Japan Marine United Corporation received a 0.7 billion yen deal for their respective parts of the design work. MHI will build the first ASEV while Japan Marine United (JMU) will be in charge of building the second one.
The defense ministry is targeting to commission the first ASEV by the end of March 2028, with the second vessel to be inducted by March 2029.
