Last month, the Japan Maritime Self-Defense Force commissioned JS Kumano, the first of its new Mogami-class multi-role frigates. The warship was built at Mitsubishi Heavy Industries facility in Tamano and is the first of a planned class of 22 ships that are destined to replace the fleet’s aging Abukuma-class destroyer escorts and Asagiri-class light destroyers.
Displacing about 3,900 tons, the new frigates have a low radar signature and will deliver new capabilities, including facilities to support the deployment of uncrewed underwater vessels and uncrewed surface vessels, and are fitted with a vertical launch system hosting surface-to-air missiles for medium-range anti-air warfare capability. The Mogami-class program is the latest in a series of projects that are upgrading the capabilities of the JMSDF, which is one of the largest navies in the world. It operates several classes of destroyers, a fleet of 21 diesel-electric submarines, two classes of helicopter carriers, maritime patrol aircraft, helicopters and mine warfare vessels. Most of these are relatively modern and equipped with the latest sensors and weapons.
But Japan doesn’t talk much about its naval capabilities because of its historical aversion to offensive capabilities following its defeat in World War II. This has been defined in Article 9 of its post-war constitution. However, as an island nation and a naval power, it has still been able to assemble a modern version of a big gun fleet, but it’s designed for defensive operations. But over the past two decades, the rise of China as a global power and North Korea’s attempts to develop long-range nuclear missiles present a two-fold threat to the island nation.
The frigates are also fitted with a variable depth sonar and towed array sonar for anti-submarine warfare missions and will be capable of conducting mine warfare. The second ship (but first-in-class), Mogami, built by MHI in Nagasaki, will be commissioned later this year and a third, Noshiro, is due to be commissioned in December.
“The basic concept of the Mogami-class is that it is a multifunctional vessel serving also as an extension of a minesweeper,” Kazuki Yamashita, a former JMSDF commander, told USNI News. “Therefore, unlike other destroyers that function as the main force of the Fleet Escort Force in various types of warfare, the Mogami-class is expected to have complementary functions to support various warfare types and also to be able to respond to [various missions], such as persistent ISR and disaster relief.”
First, Japan cannot outpace the naval construction capability of China at least not without devoting vast sums of money to defense, something that is not politically acceptable in Japan. Therefore, Tokyo has to accept secondary status in the Northeast Asian region as a naval power in terms of ship numbers compared to China’s People’s Liberation Army Navy (PLAN). But Japan can harness the latest technologies for its ships to increase naval capabilities on its existing platforms.
Second, the threat from North Korea is growing as Pyongyang’s ability to develop a successful long-range nuclear missile capability gets closer with each year. Despite attempts to limit North Korean progress through diplomacy and sanctions and although there is evidence of failed missile tests in recent years, the danger is set to increase, Japanese officials have said. . This means Tokyo has a special interest in deploying ballistic missile defense systems to counter this threat and the JMSDF provides the platforms to host this capability.
Yamashita said that efforts to modernize the JMSDF are “constantly in progress” and its latest plans come under the National Defence Program Guidelines for Fiscal Year 2019 and the Mid Term Defence Program (FY2019-FY2023) that were outlined in 2018. These plans call for a total fleet of 22 submarines and 54 destroyers. For FY2022 the Japan Ministry of Defence has requested funding of JPY5.48 trillion (about $50 billion) to allow defence spending to return to 1% of GDP following recent cuts.
One of Japan’s recent priorities is to develop unmanned systems to enhance the intelligence, surveillance and reconnaissance capabilities of the fleet. The JMSDF is also looking at increasing its firepower, with plans for a new underwater-launched cruise missiles from a VLS for its submarines.
“I believe that both technologies are necessary to improve the offensive capabilities of submarines. In addition, considering Japan’s security environment, it is expected those would be installed in the submarines in the future,” Yamashita said.
The JMSDF’s fleet of diesel submarines is its most important capability for denying an enemy sea control. On March 9, the first boat of the new 3,000-ton Taigei-class (29SS) of submarines, JS Taigei (SS-513), was commissioned. Built by MHI, these boats will have an improved combat management system and sonar and they are much quieter and more maneuverable in the water compared to the 12 earlier Soryu-class (16SS) SSKs.
“One of the characteristic differences is the use of a floating deck, which reduces noise and improve[s] shock resistance,” Yamishita said. In addition, the Taigeis are fitted with a torpedo countermeasures system, a new combat management system and the new Type 18 torpedo due to be delivered in May 2022.
The class does not have an Air Independent Propulsion system, but instead uses new Li-ion batteries from GS Yuasa to replace older lead-acid batteries that will provide additional power for extended underwater operations. The last two boats in the Soryu-class, JS Oryu (SS-511) and JS Toryu (SS-512), were the first to be fitted with Li-ion batteries and were commissioned in March 2020 and 2021, respectively, making Japan the first country to successfully adopt this technology. The second Taigei-class boat, Hakugei (SS-514), was launched by Kawasaki Heavy Industries in October 2021 and is expected to be commissioned in March 2023. Another two boats have been funded and are under construction.
Meanwhile, on the surface side, the JMSDF’s two new 27,000-ton Izumo-class helicopter carriers, which were delivered in 2015 and 20117 following an earlier pair of Hyuga-class DDHs, are undergoing a conversion to operate the F-35B Lightning II Joint Strike Fighter. USNI News reported in October the flight of two United States Marine Corps F-35Bs from JS Izumo (DDH 183) to test the modifications, with final conversion work expected in 2025. Sister ship JS Kago (DDH 184) will begin conversion this year. The cost to convert the two carriers is estimated at JPY6.7 billion. The Japan Self-Defense Force plans to buy 42 F-35Bs to arrive starting in 2023.
However, Yamishita explained that the Izumo-class was originally planned for operations as a helicopter carrier/destroyer – hence the ‘DDH’ prefix – and the refit provides only “limited improvements” to the onboard operations of F-35B. He added “even if [Izumo] were to be extensively refurbished, it can only be expected to function as an emergency [flight] deck and other supply stations at sea.”
But the bulk of the JMSDF Fleet Escort Force is provided by its destroyers that including eight ships fitted with Aegis deploying a BMD system. The latest vessels to enter service are the two 170 meter-long 8,200-ton Maya-class (27DD) destroyers, JS Maya (DDG 179) and JS Haguro (DDG 180), which were built by JMU in Yokohama and commissioned in 2020 and 2021. Equipped with a combination of the latest Baseline J7 Aegis system, SPY-1D(V) radar and AN/SPQ-9B X-band fire control radar, they fire the Standard Missile 3 Block IIA missile and are expected to be fitted with Standard Missile 6 soon.
Yamashita said the ships “will significantly improve the JMSDF’s air and missile [defense] capabilities, enabling further cooperation with the U.S. Navy.” In addition, the combination of the hull-mounted AN/SQQ-89A(V)15J sonar system and the towed array sonar system, AN/SQR-20 Multi-Function Towed Array, is also expected to improve ASW capabilities. They are the first JMSDF ships to be fitted with a combined gas turbine-electric and gas turbine propulsion system arrangement.
The Maya-class were originally called the improved Atago-class, as they are similar in size and capability to a pair of Atago-class BMD-capable destroyers that were commissioned in 2007 to 2008. Four Kongou-class ships built in the 1990s complete the JMSDF’s fleet of eight BMD-capable vessels.
North Korea’s launch of an intercontinental ballistic missile last month highlighted the need for a BMD system, as it again showed that Pyongyang is undeterred in its efforts to strive for a fully-fledged nuclear missile capability. Further missile tests are planned.
A further two Baseline J7 Aegis-equipped next-generation BMD destroyers are planned following the ministry of defense’s decision to cancel plans for a shore-based Aegis BMD system. The new vessels will be fitted with the AN/SPY-7 (V)1 solid-state radars instead of the SPY-6 radar expected on the U.S. Navy’s BMD ships.
The JMSDF’s other modern destroyers in the Fleet Escort Force include the two smaller 6,800-ton Asahi-class (25DD) destroyers that were built at MHI and entered service in 2018 to 2019. They will accompany the three Akizuki-class (19DD) destroyers that commissioned in 2012 to 2014 and are designed to protect the DDH and BMD destroyers.
Elsewhere, funding has been requested for the replacement of JS Wakasa, the JMSDF’s oceanographic research ship and a fourth Hibiki-class ocean surveillance vessels. The third Hibiki-class ship, JS Aki (AOS 5203), was commissioned in March 2021 with an advanced Surveillance Towed Array Sensor System (SURTASS) system. There are also plans for a fifth FRP-hull Awaji-class mine countermeasures vessel fitted with light detection and ranging surveillance systems that are replacing earlier wooden-hulled MCM vessels. Japan’s ATLA acquisition authority is also planning for a new MCM-capable OZZ-5 autonomous underwater vehicle that will utilize low-frequency and high-frequency synthetic aperture sonar to enhance this capability further.
In July 2021 ATLA announced a project for a new fleet of 12 next-generation Offshore Patrol Vessels. Initial specifications are for the ships to displace up to 2,000 tons, operate with a small crew and feature a large sensor payload for a specialist surveillance role. Yamashita said the new vessels are expected to “supplement some of the operational functions of each District Headquarter, such as [humanitarian aid, disaster relief] and ISR missions.”
Other future technologies include plans to develop an electronic surveillance aircraft for the JMSDF investment in long-endurance UAVs and miniature ship-based UAS; and an unmanned MCM clearance system for the Mogami-class frigates. Japan is also planning to develop a new 1,000 kilometer-plus long-range cruise missile to launch from ships, submarines, aircraft and land. MHI is developing the missile, which is expected to be ready in the mid-2020s to ensure Japan keeps pace with similar long-range missile developments in the region.
To counter future threats adequately, Yamashita said that the JMSDF needs to “establish an information superiority and improve the offensive capabilities of their weapons. This will require equipping them with various types of unmanned vehicles that operate in any space, as well as longer-range missiles that can be fired from distributed assets using networks.”
He added: “We should not take a myopic view of the security environment and just prepare for immediate threats. Rather, we should anticipate the changes that might happen in the next one or two decades and prepare for future threats.”