Japan’s Controversial Plan for Aegis-Equipped Vessels

The Japanese Ministry of Defense has requested funding for two new Aegis-equipped ships – the biggest Japanese warships since World War II – in its 2023 defense budget proposal.

The plan comes after the ministry canceled the deployment of two land-based Lockheed Martin Aegis Ashore ballistic missile defense (BMD) systems in 2020, due to concerns that the rocket booster for the interceptor missile could fall into the local community. But the alternative plan is sparking debate among military experts over whether Japan really needs such giant ships.

The ministry plans to commission the first ship by the end of fiscal year 2027, with the second scheduled to be commissioned a year later.

A spokesman at Defense Ministry told The Diplomat 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. Regarding the full complement of each ship, he declined to comment on a specific number but said the ministry is considering “a drastic reduction in manpower.” Japanese media have reported the ship will require a crew of about 110 people.

In comparison, the two Izumo-class helicopter carriers, currently the biggest ships in the Japan Maritime Self-Defense Force (JMSDF), are 248 meters long, 38 meters wide, and have a standard displacement of 19,500 tons. The ships have a crew of about 470. Meanwhile, Japan’s largest destroyers are the two Maya-class Aegis-equipped destroyers, which have a displacement of 8,200 tons and a width of 21 meters.

Many Japanese media have labeled the upcoming new ships as the “Yamato of Reiwa,” meaning the Reiwa-era version of the now-defunct Imperial Japanese Navy's Yamato, the world's largest battleship during World War II.

Military experts have pointed out that the hull was enlarged to solve the problem of the size and weight of the Lockheed Martin AN/SPY-7 solid-state radars (SSRs) that will be installed on the new ships. The AN/SPY-7 radars had initially been contracted for two land-based Aegis Ashore systems. But despite the cancellation of those systems, Japan’s Defense Ministry in 2021 selected the AN/SPY-7 radars over Raytheon’s AN/SPY-6 radars, which were originally designed for U.S. Navy (USN) warships equipped with the Aegis Combat System. Many experts in Tokyo argued that AN/SPY-6 radars should have been selected to ensure the JMSDF’s interoperability with the USN.

Building mega-ships goes against modern trends. Naval analysts say Japan needs more smaller, more compact warships such as frigates and offshore patrol vessels, rather than massive ships, to deter China’s aggressive maritime activities effectively in the East China Sea and the West Pacific.

Another problem is that the new ships will put additional burdens on the JMSDF, which already has a chronic manpower shortage. The government initially looked into the land-based Aegis Ashore system in part because it was supposed to provide around-the-clock protection against North Korean ballistic missiles by using Japan Ground Self-Defense Force (JGSDF) troops, thus reducing the burden on the current eight JMSDF Aegis destroyers that are pulling much of the weight for Japan’s missile defense.

In addition, big ships such as the Izumo class and upcoming Aegis-equipped vessels will need other escort ships and destroyers, especially ones that have anti-submarine capabilities, thus adding yet another burden to the JMSDF.

The third problem is the new ships are expected to come with a huge price tag. Japanese media, such as Kyodo News, have reported the total cost for the ships will reach at least 900 billion yen ($6.3 billion), more than double the price for the scrapped land-based defense system plan and more than five times that of the JMSDF’s latest Aegis destroyer, Haguro.

Behind the escalating cost of the new ships is a big change from the Defense Ministry’s original plan. It initially planned to build these Aegis-equipped ships as replacements for the land-based Aegis Ashore system, meant to defend against North Korea’s ballistic missiles. However, now the ministry aims to build these ships as more than just Aegis Ashore replacements at the request of some powerful lawmakers.

The spokesman at the ministry confirmed to The Diplomat that the new ships will be equipped with not only Standard Missile 3 (SM-3) Block IIA (RIM-161D) hit-to-kill interceptor missiles to defeat short-, medium-, and intermediate-range ballistic missiles, but also Standard Missile 6 (SM-6) air-defense missiles. The SM-6 provides the capability to defend against anti-ship cruise missiles in flight, both over sea and land, terminal ballistic missiles, fixed and rotary-wing aircraft, and unmanned aerial vehicles.

The ministry is obscuring the original and real purpose of building the new ships. This could be the Concorde effect, also known as the sunk cost fallacy: a psychological tendency to continue to invest money in a dubious project because of what has already been invested.