Japan Plans Giant Missile Defense Ships, Its Largest Post-WWII Surface Combatants
Japan’s ballistic missile defense capabilities are set to be overhauled by two new warships, replacing plans for the Aegis Ashore system.
The Japan Ministry of Defense has provided more details of its plans to build two huge new warships, part of a wider missile defense initiative that’s superseded an earlier proposal to install the land-based Aegis Ashore system in Japan. The as-yet-unnamed missile defense ships are expected to have a standard displacement of around 20,000 tons — more than twice as much as the current Aegis-equipped Maya class destroyers — making them potentially the biggest Japanese surface combatants since World War II.
In its budget request for Fiscal Year 2023, the Japan Ministry of Defense outlined its proposal for the two new warships, to be funded from an overall requirement of around $39.7 billion, compared with $38.4 billion for FY2022. Unconfirmed reports in the Japanese media suggest that the two new ships could come with a price tag of $7.1 billion, considerably more than the roughly $4.3 billion that the two Aegis Ashore systems were expected to cost. Overall, the Japanese defense budget has been steadily growing in recent years, reflecting the growing importance assigned to the country’s military, and the fast-developing threats emanating from both North Korea and China.
Speaking last week, the Japanese Minister of Defense Minister Yasukazu Hamada said that introducing the two big new ships in the missile defense role would allow the other Aegis destroyers to focus on other critical duties, in particular defending against potential Chinese maritime incursions.
Currently, the Japan Maritime Self-Defense Force, or JMSDF, Aegis fleet comprises two Maya class, two Atago class, and four Kongō class destroyers. The latest Maya class warships are subvariants of the Atago class, which in turn evolved from the Kongō class, a Japanese derivative of the U.S. Navy’s Arleigh Burke class destroyer.
According to figures published by The Nikkei, the warships are expected to have a length of around 690 feet and a beam of around 130 feet. This compares to a length of just over 557 feet and a width of around 73 feet for the Maya class, the latest Aegis destroyers to enter service with the JMSDF. These warships have a standard displacement of around 10,250 tons.
Indeed, previous reports had suggested that the new warships would be much closer in size to the Maya class, with a standard displacement of around 9,000 tons. This also contributed to speculation that they might be built on a modified Maya class hull.
In fact, in terms of size, the new missile defense ships would be more comparable to the Izumo class helicopter destroyers, currently, the JMSDF’s largest warships, which have a length of just under 814 feet, a width of around 125 feet, and an empty displacement of 19,800 tons, rising to 27,000 tons fully loaded.
Interestingly, the proposed new warships would be broadly similar in terms of dimensions to the World War II-era Kongō class battlecruisers, which were 720 feet 6 inches long, 108 feet 7 inches wide, with a displacement of 28,000 tons. That latter figure, of course, includes a considerable amount of armor protection that will be absent from the new designs.
It is also important to note that the figures released so far reflect only a draft plan and could be subject to change.
Regardless, the new ships will also provide a key node in the U.S. missile defense shield, making their procurement a priority for the U.S. as well as Japan.
“We believe it is an extremely important initiative to drastically strengthen our defense capabilities within five years,” Hamada said of the new warships, noting that their development process was now being accelerated.
Current plans call for the first of the new warships to be commissioned into service in late 2027, with the second following in late 2028.
Overall, though, it’s unclear at this stage what the new warships will actually look like. Although they were previously described by the Japanese media as ‘super-destroyers,’ more recently there has been speculation that they will not follow the same kind of destroyer design used in the JMSDF’s current Aegis warships.
Some concepts have shown vessels based on a catamaran or multi-hull design, which would increase stability, which is critical for optimum radar performance. More radically still, thought was given to installing the missile defense architecture on some kind of unpowered barge.
Although it now seems a monohull will be used, the final design may not necessarily have much in common with conventional destroyers or cruisers — as indicated by the relatively enormous planned width of around 130 feet. One option might be an enlarged version of the kind of hull used in the Izumo class helicopter destroyers or the slightly smaller Hyuga class.
Defense Minister Hamada pointed to North Korea’s expanding and increasingly capable ballistic missile arsenal as a factor in the requirement for the new warships. Not only is North Korea now able to launch larger barrages of ballistic missiles, but these may increasingly come from unexpected launch sites, thanks to developments in mobile ballistic missiles, both road-mobile, and rail-based. North Korea is busily developing new submarine-lanched ballistic missiles, too. At the same time, their performance and flight profiles make them harder to intercept. The new warships will be expected to be able to intercept North Korean missiles (or those launched by other hostile powers) at high altitudes.
In addition to ballistic missiles, Hamada also said that the new warships would be equipped to intercept hypersonic glide weapons, a class of weapon that is already established in China and Russia, and which North Korea is also developing. According to The Nikkei, the ability to counter hypersonic glide weapons would “be added later,” but no other details were provided. Generally, fielding interceptors to defeat these kinds of threats, which fly at Mach 5 or more, is a significant challenge.
Other key features of the new warships include a relatively small crew complement, with 110 personnel, compared to around 300 for the Maya class destroyers.
At this point, it should be recalled that the problem of personnel numbers within the JMSDF is something that has been raised before in the context of the new warships. After all, one of the original reasons to choose Aegis Ashore was the concern about the limited number of available JMSDF crews to man traditional ships. So significant is this issue that the JMSDF is currently introducing the Mogami class of multi-mission ‘destroyer’ that’s actually frigate-sized to cope with the JMSDF personnel shortage.
Other factors could also help bring crew numbers down, including increased automation, and combat tasks potentially being restricted to air and missile defense.
At the same time, crew quarters will likely be relatively well appointed, making them more suitable for long-duration deployments around the Japanese home islands.
While the new warships may not look much like the Aegis vessels currently in service, the Japan Ministry of Defense has confirmed that they will, nevertheless, take on the bulk of the ballistic missile defense duties, in particular, from these destroyers.
What is certain, therefore, is that the centerpiece of each of the two new warships will be the Lockheed Martin AN/SPY-7 Long Range Discrimination Radar that is designed to defend against ballistic missiles. These are the same radars that were originally planned to be used in Japan’s Aegis Ashore systems.
Work on the planned pair of land-based Aegis Ashore systems was suspended in 2020, with officials citing amid technical issues, rising costs, and domestic criticism. The latter included concerns that debris from intercepted missiles could land on Japanese territory and cause damage or injury, which threatened to jeopardize testing of the missile portion of the system. There has also been significant public concern about the potential health impacts of the radiation from the Aegis Ashore system’s powerful radars.
The missiles will be SM-3 MkIIA interceptors, which offer a wider engagement envelope than currently fielded SM-3 variants and which are better able to tackle a wider range of missile threats. This missile and the U.S.-Japan consortium that developed it is something we have covered on multiple occasions in the past, here, here, and here.
It's also noteworthy that Japan is not the first nation to decide to field the SPY-7 on warships. Lockheed Martin is already supplying versions of the same radar for installation on the future Canadian Surface Combatant, which will be derived from the BAE Systems Type 26 frigate design, as well as Spain’s forthcoming F110 class frigates. These designs are significantly smaller than Japan’s proposed missile defense ships. Nevertheless, the SPY-7 is a highly scalable radar, so an installation tailored for ballistic missile defense could also be larger.
Even so, it could be the case that Japan is opting for this unorthodox solution, at least in part, on cost grounds. In the past, Japan did study special-purpose ships or offshore platforms for missile defense, considering them a cheaper alternative to more large destroyers. Similar thinking was also behind the U.S. Ballistic Missile Defense Ship, or BMD Ship, that was conceived by Huntington Ingalls Industries on the basis of the existing San Antonio class landing platform dock hull. The aim was to provide a significantly more capable platform for missile defense than the existing Arleigh Burke class guided missile destroyers.
On the other hand, a missile defense vessel based on some kind of offshore platform or even on an adapted amphibious assault ship hull would be vulnerable to attacks from anti-ship missiles or submarines. It is unclear what kinds of defenses and other weapons would be included on the hulls, with the focus so far very much on the missile defense mission. This could lead to a requirement for the escort of these vessels by destroyers and submarines.
However, there have been some indications that the missile defense vessel could become a more versatile platform or at least one that has the ability to strike back with long-range cruise missile attacks against North Korean missile launchers, for instance. Last month, reports in the Japanese media suggested that officials might be looking to add a “counterattack capability” in the form of an upgraded version of the Type 12 surface-to-surface missile. This would potentially have a range of over 600 miles.
It will be fascinating to see what kind of vessels will emerge from Japan’s missile defense ship program. What is clear, is that once deployed, they will be expected to play an important role in a missile defense shield that will be expected to protect U.S. as well as Japanese interests, in a region where ballistic missiles are proliferating.
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