Japan accelerates surface fleet modernization with launch of 11th Mogami-class frigate JS Tatsuta.

On July 2, 2025, Japan’s Ministry of Defense held the naming and launching ceremony for the eleventh unit of the Mogami-class frigate series at Mitsui E&S Shipbuilding’s Tamano Shipyard in Okayama Prefecture. The new ship was officially named JS Tatsuta, continuing the Japan Maritime Self-Defense Force (JMSDF)’s tradition of naming ships after rivers. Following the launch, JS Tatsuta will proceed to fitting out and sea trials before commissioning into the JMSDF. The ceremony marks another milestone in Japan’s defense policy to field at least twelve units of the class by the end of fiscal year 2027, in line with procurement goals set under the Medium-Term Defense Program. The program aims to modernize and numerically reinforce Japan’s escort fleet amid concerns over the security environment surrounding the Japanese archipelago.
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Operational endurance and range have been prioritized in the Mogami-class design to allow a persistent deployment across Japan’s vast maritime domain. (Picture source: Japanese Navy)

JS Tatsuta (FFM-11) inherits the full design characteristics of the 30FFM program initiated in the 2010s, which evolved into the Mogami-class designation with the commissioning of JS Mogami (FFM-1) in 2022. The ship has an approximate full-load displacement of 5,500 tons, a hull length of 133 meters, and a beam of 16.3 meters. Propelled by a Combined Diesel and Gas (CODAG) system that integrates a Rolls-Royce MT30 gas turbine with MAN diesel engines, the ship can exceed speeds of 30 knots and has an endurance exceeding 9,000 kilometers. It is equipped with a 127mm Mark 45 Mod 4 naval gun, a 16-cell Mk 41 Vertical Launching System (VLS) designed to carry surface-to-air and anti-submarine missiles, two quadruple Type 17 (SSM-2) anti-ship missile launchers, a SeaRAM close-in weapon system, and two triple 324mm torpedo tubes. JS Tatsuta supports the operation of one SH-60L helicopter and is capable of launching unmanned surface and underwater vehicles to support mine countermeasures and surveillance tasks. Automation and an integrated combat system allow a crew complement of around 90 personnel, optimizing manning requirements for sustained deployments.

The origins of the Mogami-class date back to the mid-2010s, when Japan’s Ministry of Defense launched the 30FFM program to address the need for a new generation of general-purpose escort ships. The objective was to replace aging destroyers and frigates such as the Abukuma-class and Asagiri-class, while introducing more modular, flexible, and cost-effective capabilities. Mitsubishi Heavy Industries (MHI) and Mitsui E&S Shipbuilding were selected as the two lead shipbuilders, alternating hull construction between their respective shipyards. The design emphasized stealth, survivability, open architecture systems, and unmanned integration. The first ship, JS Mogami, was launched in March 2021 but faced initial delays due to the unavailability of the VLS. However, since those issues were resolved, ship production has progressed steadily, with two to three vessels launched annually. JS Tatsuta is the eleventh unit launched, and the twelfth is already under construction. The Ministry of Defense is considering expanding the class beyond the original twelve units to a possible fleet of twenty-two.

The Mogami-class is intended to serve as the core of Japan’s medium-displacement fleet, supporting a wide variety of mission profiles. These include anti-submarine warfare (ASW), anti-surface warfare (ASuW), limited area air defense, mine countermeasures, and humanitarian assistance/disaster relief (HA/DR). With its flexible architecture and room for additional mission modules, the ship can also support amphibious and special forces operations. In particular, the ship’s aviation facilities and ability to deploy unmanned systems represent a significant leap in capability compared to earlier JMSDF platforms. In addition, the compact crew size reflects Japan’s demographic constraints and the need to reduce long-term personnel costs. The use of radar-absorbent materials, an integrated mast, and enclosed sensor arrays supports stealth operations, which are increasingly important for patrols near the Senkaku Islands and along the first island chain, where Japanese forces frequently encounter Chinese vessels and aircraft.

The ships of the Mogami-class are being delivered to major JMSDF homeports such as Yokosuka, Maizuru, Sasebo, and Ominato. Commissioned units have already been deployed for various missions, including regional patrols, surveillance, and participation in multilateral naval exercises such as RIMPAC, Malabar, and Talisman Sabre. Their presence reinforces Japan’s ability to maintain situational awareness and uphold the rule of law in international waters. In particular, their role in supporting Japan’s Free and Open Indo-Pacific strategy makes them valuable assets for interoperability with the U.S. Navy, Royal Australian Navy, and other partner fleets. Their size and versatility also make them suitable candidates to accompany larger JMSDF task forces built around Izumo-class helicopter destroyers or Maya-class Aegis destroyers. Furthermore, their distributed capabilities and mission flexibility align with evolving concepts of operations such as distributed maritime operations and multi-domain integration.

From an industrial and procurement standpoint, the Mogami-class ensures continuity of Japanese naval shipbuilding capacity across two major private-sector shipyards. The alternating build scheme between MHI and Mitsui E&S has maintained production stability and met procurement targets despite initial delays. The program relies on domestic suppliers for major systems, including sensors, missiles, and communications equipment, supporting Japan’s policy of defense industrial independence. Although no confirmed export orders have been signed, the class has been promoted as a candidate for international sales, particularly in Southeast Asia. The relatively compact size, lower crew requirements, and multi-mission design could appeal to countries seeking modern frigates despite limited manpower or budgets. With JS Tatsuta now joining the fleet, the program continues to gain momentum as a central element of Japan’s naval strategy for the coming decades.