The Japanese Ministry of Defense says in its proposed budget for 2023 that it aims to build two ships with a displacement of 20,000 tons. Both ships must be capable of ballistic missile defense (BMD), the Japanese defense minister announced, according to USNI News.
SM-3 missile leaves the VLS of a US Navy ship. (Photo: Missile Defense Agency)
With the construction of both ships, Japan is now definitively abandoning plans to build two BMD systems on land (called AEGIS Ashore). As early as June 2020, Japan announced that it is abandoning the ‘AEGIS on land’ modules due to the risk of damage to the environment. The main reason was that there was no guarantee that the propellants of the SM-3 interceptor missiles, which are rejected by the missile shortly after takeoff, would land within the designated safety zones.
Defense against ballistic missiles would, with the decommissioning of AEGIS Ashore, be taken over by the Japanese Navy’s eight AEGIS destroyers. But the two new BMD ships should reduce the workload of those eight, as they will also be used to deter ships and aircraft in southwestern waters, the defense minister said Friday.
Little is currently known about the two new ships, apart from the fact that these ships have a displacement of 20,000 tons, a length of approximately 210 meters and a width of approximately 39.6 meters. By modern standards these would be large ships.
With this, the new ships would fall into the same category in terms of displacement as the light aircraft carriers of the Izumo class, but then 30 meters shorter and two meters wider. In addition, the new Japanese BMD battlecruisers would be 5,000 tons heavier than the Zumwalt-class destroyers and up to 9,000 tons heavier than the Chinese Type 055/Renhai-class cruisers. The only ships that are heavier and fulfill a similar role are the Russian Kirov-class battlecruisers with a displacement of 24,000 tons.
Despite their enormous size, they are not unique in Japanese history. Numerous Japanese battleships were much heavier than 20,000 tons. The Yamato class battleships (largest ever built) measured 65,000 tons.
The significant displacement of water may be necessary to provide stability to the radar installation on board. The latest AEGIS ships operate with the AN/SPY-7 radar, but AEGIS onshore systems use the LRDR radar, which is up to twice the size of the SPY-7. It is known that Japan has already purchased components of the AEGIS onshore systems, but there is no confirmation if the radar systems were part of this purchase.
Commissioning of the ships is to take place in 2027 and 2028, which gives some time to design the ship. Japan may have designed these new AEGIS battlecruisers based on existing ships. Both the Huyga and Izumo class light aircraft carriers are possible candidates as the dimensions and displacement are close to the intended design. The Izumo class appears to be the most likely candidate to serve as the basis for the design of these battlecruisers. The existing design can easily be shortened and built less tall to lean closer to the already known design of the BMD variant of the San Antonio class.
But the design of the American San Antonio class can also serve as a basis. In 2014, the American shipyard Huntington Ingalls Industries presented a variant of the San Antonio-class LPDs, which is specialized in BMD. This BMD variant has an enlarged radar installation on the superstructure in combination with 288 Mk 41 or 144 Mk 57 vertical launch systems in the aft part of the ship.
JS Maya is 170 meters long and has a displacement of up to 10,000 tonnes. (Photo: Japan Maritime Self-Defense Force)
As mentioned, Japan’s main concern is the risk of damage when launched from a land-based BMD system. Mounting these systems on battlecruisers and deploying them at sea significantly reduces the risk of collateral damage from falling debris. However, the disadvantage of these battlecruisers is the operational deployability in numbers. The two AEGIS systems on land have now been replaced by two battlecruisers. However, the need for maintenance, modernization and upgrading of the crew means that in reality there will often only be one ship in operation. Since North Korea poses the biggest threat, these ships will most likely be deployed in the Sea of Japan. From a central position in this sea, one battlecruiser can provide the necessary security, but there are no reserves.
The battlecruisers offer a tactical advantage as they are mobile and have no fixed location unlike the land-based BMD system. This makes the Japanese missile defense system less vulnerable to a surprise attack, as its location changes and adapts so that enemy units must first be able to track and detect them.
The operational deployment of both battlecruisers in the Sea of Japan should also enable AEGIS destroyers to be released for other tasks. Japan currently operates eight of these destroyers, two of the Maya class, two of the Atago class and four of the Congo class. As a result, these destroyers can be used more for maritime deterrence and patrol duties southwest of Japan. The mobility of the battlecruisers also allows these ships to be deployed against the threat of Chinese ballistic missiles flying over the East China Sea and the Ryukyu Islands.
In addition to deploying SM-3 missiles against ballistic missiles, the ships can also use the SM-6 missionary against air targets and anti-ship missiles. It is possible that these battlecruisers can also be equipped with the second generation of the Type 12 missiles. This improved variant has a better stealth design and increased range from 200 to 900 kilometers. Type 12 can attack both sea and land targets. Equipped with the Type 12, the Japanese battlecruisers can assume the role of an arsenal ship in future maritime conflicts. The second-generation Type 12 Missionary is scheduled to enter service in 2026, a year before the first battlecruiser.
If the battlecruisers are similar to the BMD variant of the San Antonio class, they will have 288 launch cells each. This is 2.5 times the number of launch cells on a Type 055 Renhai cruiser of the Chinese People’s Navy or 3 times more than the number on an Arleigh Burke class destroyer. With only two battlecruisers, Japan can match a fleet of five Chinese cruisers. This makes the Japanese battlecruisers an important component of the future maritime deterrence against the Chinese People’s Navy and the restoration of the maritime balance of power in the region.
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