November 15, 2024: For over a year U.S. Marine Corps F-35B vertical takeoff (VTOL) fighters have operated from one of the two new Japanese aircraft carriers to test their flight decks for heat resistance to the F-35 B's engines. The two Japanese carriers are called helicopter destroyers that look like small aircraft carriers, which is what they actually are. The post-World War II Japanese constitution prohibits Japan from having aircraft carriers but the helicopter destroyers were modified to use the F-35B stealth fighter. Japan has 42 F-35Bs on order, thus the need for American F-35Bs to test the ability of the Japanese carriers to handle this aircraft. The U.S. Navy has modified several Marine Corps assault carrier-type ships to handle F-35Bs. These ships are also receiving, by 2025, new smaller vessels to put soldiers ashore.

Japan is making a big investment in F-35s operating from land and seagoing bases. Land bases are no problem but since 2017 Japan has had two 27,000 ton Izumo class DDH type ships, called destroyers, operational. These ships look exactly like an aircraft carrier. These Izumo class ships can carry up to 28 helicopters or up to twelve F-35Bs. The carriers are armed only with two 20mm Phalanx anti-missile cannons and launchers with sixteen ESSM missiles for anti-missile defense. The DDH have powerful engines capable of destroyer-like speeds of over fifty-four kilometers an hour. There are also more medical facilities than one would expect for a ship of this size. Izumo does have considerable cargo capacity, which is intended for moving disaster relief supplies quickly to where they are needed. Some of these cargo spaces can be converted to berthing spaces for troops, disaster relief personnel, or people rescued from disasters, as well as additional weapons and equipment needed to support F-35B fighter-bombers.

Izumo can carry and operate F-35Bs because modifications were made to the flight deck to handle the extremely high temperatures the F-35B generates when taking off or landing vertically, like a helicopter. When the first DDH entered service in 2015 Japan made no mention of buying F-35Bs or modifying the LPH flight decks to handle the F-35B. The Izumos already have an elevator (to the hangar deck under the flight deck) powerful enough to carry an F-35B fighter as well as the lighter helicopters. Japan also has two older, smaller 19,000-ton Hyuga-class helicopter carriers that could be upgraded to carry and use a smaller number of F-35Bs but currently just operate 18 helicopters each.

These two Izumo-class fast carriers are a powerful addition to the Japanese Navy, which is already the second largest in East Asia, second only to China. Its combat ships are all of modern design with well trained and experienced crews. For example, in 2022 Japan put into service two of twenty-two Mogami-Class 30FFM multi-mission frigates. The first two ships, the Mogami and Kumano began construction during October 2019 but the yard building Kumano took the lead, putting their ship in the water 11 months later, four months before the Mogami. The rival builder closed the gap and was ready for service in April, one month after Kumano. The Mogami class will eventually replace some destroyers as well as existing frigates. Currently six Mogami’s have been completed and four are under construction. By 2027 Japan expects to have twelve Mogami’s in service. Each ship costs about $500 million.

Japan, along with China and South Korea, are the largest shipbuilding nations in the world and produce, in terms of tonnage, over 95 percent of the commercial shipping built annually. For centuries the major manufacturer of commercial ships tended to develop and build the most innovative and numerous warships. This is how the United States became the leading warship supplier after World War II (1945).

European nations rebuilt their shipbuilding industries after World War II and became and remain major competitors. Later in the 20th century China, Japan and South Korea became and remain major commercial shipbuilders and that enabled them all to design and build their own warships. The U.S. is now a minor component of commercial shipbuilding and having problems building world-class warships and doing it on time and under budget.

The 5,500-ton Mogami 30FFM ships are an example of successful innovation and speed in implanting the new concepts The Mogami’s take the multi-mission angle seriously. They are equipped for mine-hunting as well as mine-laying. In addition to a 127mm gun, each ship carries eight anti-ship missiles, there are eleven SeaRAM anti-aircraft/missile missiles with a range of ten kilometers and 16 VLS cells that will eventually carry larger Chu-SAM anti-aircraft missiles with a range to 50 kilometers. Some VLS cells can also contain cruise missiles. There are twelve lightweight anti-submarine torpedoes. There is a ramp in the rear for launching and recovering two types of naval drones. One is an Unmanned Underwater Vessel while the other is an Unmanned Surface Vessel. Mogami’s also have several RIB Rigid Inflatable Boats for boarding parties. A helicopter is also carried and that can be replaced by two or more UAVs.

The Mogami’s are stealthy designs that are difficult to detect with radar. These ships carry active and passive-heat sensing sensors. There are ASW anti-submarine warfare and mine-hunting sonars. The active radars can also carry out jamming and other EW, Electronic Warfare, tasks. All these sensors are integrated into a single fire control system. There are two autocannon equipped with RWS Remote Weapons Stations. For defense there are electronic and chaff decoys to defend against incoming missiles or aircraft. Top speed is 55 kilometers an hour and crew size is 90 personnel, which is about half what ships this size normally have. There is a lot of automation on the ship, which accounts for the relatively small crew. The Japanese automation works because, as a major civilian shipbuilder, crew automation is a key component of success in world markets. Japan pioneered many of the earliest ship automation technologies.

The Mogami 30FFM ships were originally designed to be destroyers but while planning equipment and weapons layout it was realized that these ships could be multi-mission ships and the designation was changed to frigate. The Mogami’s will be built in batches, with an initial batch of eight, followed by two or three more batches, each improving on the earlier batch. The 30FFM already has one export customer. Indonesia will get four modified to Indonesian needs Batch One ships with another four built in Indonesia with Japanese assistance.

Currently the Japanese Navy has 155 combat and support ships. There are four helicopter carriers, 24 submarines, 36 destroyers, six Mogami class frigates, 21 mine warfare ships, six 240 ton patrol vessels, and three surveillance ships equipped with towed sonar systems. There are six training ships and dozens of support and logistics ships.

The current frigates are six 2,600-ton ships delivered in the 1990s. In the 1980s, when these frigates were designed, 11 were planned. With the end of the Cold War in 1991 the number was cut to six. Mogami’s are replacing eight 35 year old 5,200-ton destroyers and six 2,250-ton equally old Destroyer Escorts. Japanese submarines are very quiet and lethal diesel-electric boats, most with AIP air-independent propulsion that allows submerged operations lasting several weeks.