DE Abukuma Class
The Abukuma-class destroyer escort is a class of six general-purpose destroyer escorts (referred to as frigates by other navies) that have served in the Japan Maritime Self-Defense Force (JMSDF) since the late 1980s. The ships are known for being the first Japanese combatants with stealth technology and advanced electronic warfare capabilities.The Abakuma class escort ship was planned for missions such as antisubmarine patrol operations and attack of surface vessels in the coast sea area. Specific improvements include improved characteristics and improvement of habitability. The hull form is inclined to "V" shape in order to make the radar cross section decrease at an inclination to the side. However, the upper areas are like the former escort ships, which probably means that the stealth characteristics are limited. If the anti-aircraft missile and the helicopter are excluded, it is a match to other escort ships, since for the first time it has the air search radar on a DE type ship.
In 1991, the 3rd and 4th ship of 'Abukuma' type DE vessel 'Oyodo' and 'Sendai' were constructed at Mitsui Engineering and Shipbuilding CO., Ltd (MES) and Sumitomo Heavy Industries, Ltd.(SHI). The propulsion system was CODOG type with each two of Spey gas turbine and diesel engine. The gas turbines were manufactured by KHI, the diesel engines by Mitsubishi Heavy Industries, Ltd. (MHI).
The ships use a Combined Diesel or Gas (CODOG) propulsion system, giving them a maximum speed of 27 knots (50 km/h). As to the MIA gas turbine Auxiliary Generating Engine which was originally developed by KHI, one set of MIA-02 type gas turbine (1,000kW) is installed on each "Hatsuyuki" type DD vessel (total 12 ships), two sets are installed on each "Asagiri" type DD vessel (total 8 ships), and one set is installed on each "Abukuma" type DE vessel (total 6 ships).
The Abukuma class was developed to replace older destroyer escorts and provide enhanced anti-submarine warfare (ASW) and anti-surface warfare (ASuW) capabilities for coastal patrol and open-ocean fleet support. The ships were the first in the JMSDF to incorporate stealth design elements. Their hulls are angled to reduce radar cross-section, a feature ahead of its time for this class of vessel. The class was also the first of its kind in Japan to feature the Naval Tactical Data System and OYQ-7 combat direction system, as well as electronic countermeasures (ECM).
The six Abukuma-class destroyer escorts, commissioned between 1989 and 1993, had a quiet but vital operational history primarily centered on coastal defense and anti-submarine warfare (ASW) missions for the Japan Maritime Self-Defense Force (JMSDF). Their operational roles were crucial during a time of post-Cold War reorganization within the JMSDF.
Throughout their service, the Abukuma-class vessels were primarily used for patrolling Japan's territorial waters and protecting its maritime interests in coastal areas. Anti-Submarine Warfare (ASW) was a core mission for the ships. They were built with advanced anti-submarine rockets (ASROC) and torpedoes to counter the significant submarine threat posed by the Soviet Navy during the Cold War.
With their Harpoon anti-ship missiles, the destroyer escorts also had an Anti-Surface Warfare (ASuW) role in engaging enemy surface vessels. The ships regularly participated in exercises with both the JMSDF and allied navies, such as the US and South Korea, to build interoperability. For example, JS Abukuma and JS Chikuma hosted Australian ships in 1993. In 2009, JS Abukuma participated in a joint rescue training exercise with the South Korean navy.
In March 1999, JS Abukuma and other JMSDF escorts tracked a suspicious North Korean spy vessel off Japan's Noto Peninsula. This was one of the first times Japan invoked its "maritime security action" to counter an infiltrator. JS Abukuma was among the naval forces dispatched to aid survivors and assist in disaster relief efforts following the 2011 Great East Japan Earthquak and tsunami.
The Abukuma class and its crew were subject to periodic fleet reorganizations. For example, in 2010, JS Abukuma and its corps were transferred to a different escort unit and homeported in Kure. After more than three decades of service, the Abukuma-class ships are nearing the end of their operational life within the JMSDF.
The Mogami-class frigates are a major leap forward from the older Abukuma-class destroyer escorts, featuring advanced stealth, enhanced automation to reduce crew size, and greater multi-mission versatility. While both classes employ some stealth technology, the Mogami class was designed with a more complete signature reduction approach based on modern stealth fighter research.
The first retirement was scheduled for 2027, with the ships being replaced by the newer, more automated Mogami-class frigates.
DE Abukuma Class - Design
With a standard displacement of 2,000 tons and a full load of 2,550 tons, the ships are 109 meters long with a 13-meter beam. It has a top speed of 27 knots and is armed with various anti-ship missiles, anti-submarine rockets and torpedoes along with a 76mm main gun and 20mm closed-in weapon system. The JMSDF operated six Abukuma-class destroyer escorts, which were constructed from 1988 to 1991.
The Abukuma-class ships are equipped with a balanced array of weapons for their designated anti-submarine and anti-surface roles.
- Anti-ship missiles: Eight RGM-84 Harpoon anti-ship missiles [a pair of 4-missile box launchers] provide a potent, long-range punch against enemy vessels.
- Anti-submarine rockets (ASROC): One Type 74 octuple ASROC (Anti-Submarine ROCket) launcher fires ASROC anti-submarine rockets.
- Torpedoes: Two HOS-301 triple-tube launchers fire lightweight 324mm ASW torpedoes.
- Main gun: A 76mm Oto Melara dual-purpose gun serves as the primary armament for engaging surface and air targets.
- Close-in weapon system (CIWS): A Phalanx 20mm CIWS provides a last line of defense against incoming missiles and aircraft.
- Radars: They are equipped with the Japanese-built OPS-14 air-search radar and OPS-28 surface-search radar.
- Sonar: A bow-mounted OQS-8 medium-frequency sonar is used for anti-submarine detection.
- Electronic warfare: The Abukuma-class was the first JMSDF destroyer escort with electronic countermeasures (ECM) capability, featuring an OLT-3 jammer and chaff launchers for decoy deployment.
The Abukuma-class destroyer escorts, commissioned in the early 1990s, incorporated early, limited stealth technology that significantly lags behind the comprehensive signature reduction of modern warships like the Mogami class. Its limitations stem from a design philosophy that only partially applied stealth principles, primarily to the hull, while leaving many radar-reflective surfaces exposed.
Unlike modern stealth ships with angular, faceted superstructures and enclosed masts, the Abukuma class retained a conventional superstructure with traditional vertical surfaces. These vertical surfaces create strong, detectable radar returns. The vessel features various deck-mounted equipment, such as the Oto Melara gun, Phalanx CIWS, and missile launchers, which are all highly reflective. In contrast, more advanced stealth ships often use enclosed main guns and flush-mounted missile launchers to reduce their radar cross-section.
The positioning of weapons like the Harpoon missile launchers on the deck, rather than in an internal vertical launching system (VLS), creates more opportunities for radar reflection. The class does not have an integrated or enclosed mast design, which is a key feature of modern stealth ships. The exposed antennas and sensors on a traditional mast produce many radar returns.
The limited stealth shaping of the Abukuma class likely only reduces its Radar cross-section (RCS) from certain angles. A modern warship is designed to reduce its RCS from all angles, creating a much smaller and more consistent radar signature. The early design likely did little to mitigate the ship's infrared signature. Modern stealth ships often include features to cool engine exhausts and mask heat, making them less visible to infrared sensors. While the CODOG propulsion offers quieter operation at low speeds with diesel engines, the vessel lacks the advanced acoustic quieting measures (e.g., raft-mounted machinery and advanced propeller designs) of modern warships designed to minimize detection by submarines.
The limitations of the Abukuma's early stealth design are best highlighted by comparing it to the modern Mogami class. The Mogami class has a fully integrated and enclosed mast, flush-mounted VLS cells, and enclosed weapons, resulting in a much cleaner and lower-RCS profile. Its design is based on decades of lessons learned from advanced stealth fighter programs and experimental naval vessels, rather than the partial approach of the Abukuma class.
The Abukuma-class countermeasures are considered very limited against modern anti-ship missiles. The vessel's defensive systems were designed in the 1980s and have not been significantly upgraded to keep pace with modern missile technology. Its anti-missile defense is a "last-ditch" effort, relying on its CIWS and chaff launchers to defeat threats that have already broken through outer defenses.
The Fujitsu OLT-3 jammer and NEC NOLQ-6C electronic warfare system were cutting-edge Electronic countermeasures (ECM) for their time, but are not built to counter the sophisticated electronic warfare used by modern missiles. Modern anti-ship missiles are more agile, use more advanced radar homing systems, and are less susceptible to older jamming techniques.
The Mk 36 SRBOC Chaff and Decoy Launching System launches decoy rockets to create a large radar-reflective cloud, which can lure older radar-guided missiles away from the ship. However, modern radar-homing missiles have advanced ECCM (Electronic Counter-Countermeasures) capabilities and can often distinguish the large, stationary chaff cloud from the maneuvering ship. This makes chaff less effective than it once was, especially against coordinated, multi-missile attacks.
The Phalanx Close-in Weapon System (CIWS) is a 20mm automatic cannon designed to be the final layer of defense against incoming missiles. While effective against some older, slower anti-ship missiles, it has serious limitations against modern threats. It is not effective against saturation attacks, where a volley of multiple missiles overloads the system's ability to engage individual threats. Hypersonic speeds: Its reaction time is too slow to effectively track and destroy modern hypersonic missiles. The debris from a hypersonic missile shot down at close range could still critically damage the ship. Modern missiles can perform high-G maneuvers in their terminal phase, making them difficult for the Phalanx to target effectively.
Plans to install a more capable Mk 31 Rolling Airframe Missile (RAM) system were never carried out. RAM offers a significantly more effective, longer-range defense against anti-ship missiles than CIWS, but is absent from the Abukuma class.
It's important to remember that these countermeasures were never meant to serve as a primary defense. The Abukuma-class vessels were designed for coastal anti-submarine warfare (ASW) and were expected to operate under the protective umbrella of more capable fleet air defenses. Against modern, dedicated anti-ship threats, their current countermeasures provide only a last, and very limited, line of defense.
DE Abukuma Class - Philippine
The Philippine Navy is transitioning from a coastal defense force to a more capable fleet with regional reach by acquiring Japanese destroyers. In 2025, Japan announced a proposal to transfer six of its decommissioned Abukuma-class destroyer escorts to the Philippine Navy. The transfer of these warships is intended to boost the Philippines' maritime defense capabilities amid rising tensions in the West Philippine Sea (South China Sea). — At 2,000 tons, the Abukuma-class destroyer escorts will be some of the largest platforms in the Philippine fleet.
Following a bilateral meeting in June 2025, Japan offered to transfer up to six Abukuma destroyers to the Philippines. The Philippine Navy (PN) on 06 July 2025 confirmed the "possible transfer" of the Japan Maritime Self-Defense Force (JMSDF)'s Abukuma-class destroyer escorts. The PN undertookr a Joint Visual Inspection (JVI) of the ships following the official invitation from Japan's Ministry of Defense.
"This planned inspection forms part of exploratory discussions on the possible transfer of these naval assets to the Philippines. Designed for anti-submarine and anti-ship warfare, the Abukuma-class destroyer escorts are known for their reliability and versatility, which align with the PN’s operational requirements in protecting the country’s maritime domains," the PN said in a statement.
The Abukuma-class destroyer escorts have a displacement of 2,000 gross tons and a length of 109 meters and a beam of 13 meters. It has a top speed of 27 knots and is armed with various anti-ship missiles, anti-submarine rockets and torpedoes along with a 76mm main gun and 20mm closed-in weapon system. The JMSDF operated six Abukuma-class destroyer escorts, which were constructed from 1988 to 1991.
Following an assessment of the vessels in August 2025, Japan was expected to transfer some or all of the ships to the Philippines. Japan is transferring both decommissioned and new warships to allies, including the Philippines and Australia, in a major strategic shift. These transfers are a break from Japan's post-World War II pacifist stance and are part of its strategy to counter China's growing military influence in the Indo-Pacific region.
Japan announced plans to transfer six used Abukuma-class destroyer escorts to the Philippine Navy. This transfer is intended to help the Philippines bolster its maritime defense capabilities amid rising tensions with China in the South China Sea. The Abukuma-class destroyer escorts are anti-submarine and anti-ship combat vessels that were commissioned in the early 1990s. This transfer will be the largest of its kind from Japan in modern history.
To navigate its constitutional ban on exporting lethal weapons, Japan is reportedly planning to treat the transfer as a "joint development project." This will allow for the customization of the warships for the Philippine Navy. The Philippine Navy conducted an assessment of the vessels, with a potential transfer by 2027. This was the latest in a series of defense cooperation initiatives between Japan and the Philippines, which have previously included the provision of patrol vessels, surveillance aircraft, and radar systems.
The move would significantly boost the Philippine Navy's anti-submarine (ASW) and anti-ship (ASuW) capabilities, but Manila faces significant challenges in sustaining and integrating these older vessels. The Abukuma class, while aged by Japanese standards, offers a major upgrade over many of the Philippines' current surface combatants, many of which are decades old. The vessels would provide a substantial increase in anti-submarine and anti-surface firepower, including Harpoon anti-ship missiles and ASROC anti-submarine rockets.
Acquiring these capable, albeit second-hand, warships would significantly enhance the Philippine Navy's ability to patrol its exclusive economic zone (EEZ) and potentially deter Chinese maritime aggression. The transfer would deepen the strategic military and defense-industrial relationship between the Philippines and Japan.
As second-hand vessels, the Abukuma class will require significant investment in maintenance and logistics to remain operational. The Philippine Navy must assess whether supply lines for spare parts and repairs can be secured. The Philippines must upgrade its naval bases to support these larger vessels. Many existing facilities are only equipped for smaller ships, and current naval modernization plans have already strained infrastructure.
The Abukuma class's countermeasures are dated and not fully effective against modern anti-ship missiles, which can overwhelm the vessel's single Phalanx CIWS and electronic warfare systems. The Philippine Navy must consider if upgrades are necessary and financially viable. The Philippine Navy will need to assess how the Abukuma-class ships can be integrated into its existing fleet, potentially requiring costly and time-consuming modifications and refits.
To proceed with the transfer, Japan will likely use a "joint development" arrangement to get around its constitutional restrictions on exporting lethal weapons. Under this approach, the Philippines would receive the vessels as part of a broader cooperation agreement that includes installing new equipment and systems requested by Manila. Philippine officials have been inspecting the vessels to conduct a cost-benefit analysis. A decision on the transfer could be made by 2027, when the first Abukuma vessel is scheduled for decommissioning.
Namesakes
Jintsu, a 5595-ton Sendai class light cruiser, was built at Kobe, Japan. She was completed at the end of July 1925 and for the next three years mainly served with other light cruisers. Soon after the commencement of the Pacific War in December 1941, Jintsu and her destroyers took part in the invasion of the southern Philippines. On 12-13 July 1943, while escorting destroyer transports taking troops to Vila, on Kolombangara, she encountered a superior force of Allied cruisers and destroyers. Hit hard by gunfire from the cruisers USS Honolulu, USS St. Louis and HMNZS Leander, and by a destroyer's torpedo, Jintsu broke in two amidships and sank with the loss of nearly 500 of her crew.
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