These 5 Weapons Are the Backbone of Japan's Mighty Navy

By Kaijō Jieitai (海上自衛隊 / Japan Maritime Self-Defense Force) -, CC BY 4.0,
September 26, 2019 Topic: Technology Region: Asia Blog Brand: The Buzz Tags: JapanJapanese NavyJDFAmericasJapanese Carriers

These 5 Weapons Are the Backbone of Japan's Mighty Navy

Mighty warships and subs.


Key point: Japan is still a power to be reckoned with.

The modern Japan Maritime Self Defense Force trace its roots to the Imperial Japanese Navy. Established in July 1869, the Imperial Navy was one of the first formal institutions—military or otherwise—of a new, modern Japan.


The current-day Maritime Self Defense Forces (MSDF), created during the 1950s, is the result of lessons learned during World War II. The American blockade of the Home Islands led to widespread hunger and economic decline. Modern Japan is still heavily reliant on secure sea lanes, and the MSDF was geared heavily toward anti-submarine and anti-mine warfare. The end of the Cold War did little to change that.

The rise of the People’s Liberation Army Navy (PLAN) has prompted the MSDF to undertake long-overdue changes. In response, MSDF ships are becoming larger and more capable. The end result should be a Maritime Self Defense Force capable of defending against the PLAN  while assisting allies and protecting Japanese interests overseas. With that said, here are five of the MSDF’s most lethal weapons of war.

Hayabusa-class Patrol Craft:

Japan’s version of the littoral combat ship, the six fast patrol craft of the Hayabusa (Falcon) class are unique in the MSDF. Similar to the “Streetfighter” littoral combat ships originally envisioned by the U.S. Navy, they are Japan’s only surface combatants under 2,500 tons, maxing out at 240 tons fully loaded. Pound for pound, the Hayabusas are the most lethal ships in the fleet.

The small size and agility of the Hayabusa class allows them to hide out among Japan’s many island chains and coastline, conducting hit and run missile attacks on much larger enemy ships. In wartime they could be assigned to the Ryukyus against China, or the southern Kurils against Russia.

Three General Electric GM500 gas turbines give the Hayabusas a top speed of 46 knots. Rather than traditional propellers, the scrappy little patrol boats are powered by three pump jet propulsion units, which provide increased maneuverability, improved shallow water performance, and a lower sonar signature.

Despite their size, the Hayabusa class is packed with offensive weaponry.  Forward of the bridge and mounted in a stealthy turret is a 76mm OTO Melara gun, common in Western navies and capable of engaging surface targets. The ships also carry four SSM-1B anti-ship missiles, the same as carried on the Atago class. Armament is rounded out by a pair of .50 caliber machine guns.

The main downside of the Hayabusas is their lack of defensive armament. Primary defensive systems are a pair of Mark 36 Super Rapid Bloom Offboard Countermeasures Chaff and Decoy Launching Systems. The Mark 36 is capable of launching chaff (to fool off radar-guided missiles) or infrared decoys (to throw off infra-red guided missiles). The 76mm gun can be used against aircraft and missiles but is not ideally suited to the task.

Atago-class Aegis Destroyer:

The Atago-class destroyers are some of the most capable surface warships in the world. Modeled after the American Flight IIA Arleigh Burke destroyers, the Atago class is capable of a little bit of everything, from engaging targets in near space to anti-submarine warfare, and capable of doing it all extremely well.

The most important part of the Atago class is the combination of the SPY-1D Aegis radar system with SM-2 surface to air missiles. The Aegis combat system is capable of detecting aerial threats out to 100 miles, from cruise missiles to high-flying aircraft, and dealing with massed attacks of both. This makes, the Atagos, like the American Ticonderoga-class cruisers and Arleigh Burke-class destroyers, the prime air defense asset of any naval task force.

Unlike the previous Kongo class, the Atago class lacks a ballistic missile defense capability. As both China and North Korea make advances in ballistic missiles, Japan has decided to upgrade both ships to help take part in the BMD role. A contract for $124 million in Aegis upgrades to both Atago and Ashigara was awarded to Lockheed Martin on May 27th.

The Atago class features one Mark 45 5-inch naval gun, the same used on American surface ships, housed in a stealthy turret. The gun is capable of engaging surface targets, providing naval gunfire support, and engaging aircraft and missiles. Further gun armament is provided in the form of two Phalanx CIWS close-in weapon systems.

The Atago class can also hunt and destroy enemy submarines with its hull-mounted AN/SQQ-89 undersea warfare combat system, which combines an active/passive sonar system with ASROC rocket-propelled torpedoes. The system can also input and combine data from embarked SH-60J/K helicopters, which the Atago class typically carries at least one. Like American surface ships, the destroyers are also equipped with two triple 324-millimeter anti-submarine torpedo mounts for close-range work.

Finally, the class is fitted with eight SSM-1B anti-ship missiles. Similar to the American Harpoon, the SSM-1B has a internal navigation system/active radar seeker system and can strike targets at ranges of up to 180 kilometers. The missile packs a 255 kilogram high explosive warhead.

There are currently two Atago-class destroyers, with two more on order.

Osumi-class Landing Ship:

The three Osumi-class tank landing ships comprise Japan’s dedicated amphibious transport fleet. Although the ships resemble small aircraft carriers, with a full-length 130 meter long flight deck, they were not built with a hangar or any permanent aviation support facilities.

The presence of tank landing ships in the MSDF is curious as Japan had forsaken amphibious warfare as an offensive—and thus prohibited—military capability. Japan is however archipelago split up among four major and hundreds of minor island, and the Osumi class is thus useful for ferrying tanks and other armored vehicles from one part of Japan to the other.

The Osumi class can carry 1,400 tons of cargo, 14 Type 90 main battle tanks or up to 1,000 personnel. A single ship can carry a company-sized mechanized landing force, and temporarily embark up to two CH-47J Chinook helicopters for heliborne landings.

Armament for the Osumi class is light, consisting of just two Phalanx close-in weapons systems. The Osumi class is equipped with a well deck, a floodable compartment in the rear of the ship that can accommodate two American-designed LCAC hovercraft, traditional landing craft, and amphibious assault vehicles.

Experts believe the peculiar layout of the Osumi class—a ship with a full-length flight deck but not a hangar—was a testing of the waters to determine if building an actual aircraft carrier was politically feasible.

Izumo-Class Helicopter Destroyers:

The Izumo-class “helicopter destroyers”, at 27,000 tons fully loaded and more than 800 feet long, are the largest naval vessels constructed by postwar Japan. Officially a “helicopter carrier-type escort/destroyer”, Izumo was built at the Japan Marine United shipyards at Yokohama.

Izumo bears a strong resemblance to traditional aircraft carriers. With a full length flight deck and hangar, each Izumo can accommodate and service up to 14 helicopters. The ability to operate multiple SH-60 helicopters at once give the Izumo a powerful anti-submarine capability, capable of searching for and destroying enemy subs over a wide area. For close-range anti-submarine work, the ships are, like the Atago class, equipped with two triple 324-millimeter torpedo banks.

Izumo can also be used to support amphibious operations. During the 2013 U.S.-Japan Dawn Blitz exercises, her smaller sister ship JS Hyuga acted acted as a floating base for CH-47J Chinook transport and AH-64J Apache attack helicopters. In that role, Izumo resembles the old Iwo-Jima class helicopter carriers operated by the U.S. Navy.

Following Japan’s order of 42 F-35A fighters in 2011, experts have speculated that Japan could order a small number of the vertical takeoff and landing F-35B variant and fly them off the Izumo class. Unfortunately, given Japan’s tight fiscal situation that appears unlikely. A retired MSDF commander, Vice Admiral Yoji Koda, stated earlier this year that the funds for doing so “would have to be found by eliminating another force element”.

The Izumo class relies on other ships for protection against mass aerial attacks. For last-ditch defense it is equipped two Phalanx close-in weapons systems and two SeaRAM point defense missile launchers. Passive defenses include an electronic warfare suite, Mk. 36 launchers akin to those on the Hayabusas, and a floating acoustic jammer.

Two Izumo destroyers are planned, with the second ship currently under construction.

Soryu-class Diesel Electric Submarines:

Japan’s Soryu-class submarines are considered some of the most advanced non-nuclear attack submarines in the world. The Stirling air independent propulsion system, licensed from Sweden, allows the Soryu class to remain underwater far longer than other diesel electric designs. At 4,100 tons submerged, they are Japan’s largest postwar submarines.

The Soryu’s main armament consists of six bow-mounted torpedo tubes, with a total of 20 Type 89 high-speed homing torpedoes and American-made Sub-Harpoon missiles. As Japan debates future acquisition of conventionally-armed cruise missiles, the class could become the carrier vehicle for an indigenous cruise missile system.   

A drawback of the class is a relatively short operating range. Japan’s Cold War submarine doctrine stressed the defense of the Tsugaru Strait, Tsushima Strait, Kanmon Strait, and the Soya Strait, all of which are relatively close to Japan. The range issue was not considered a problem, but as the submarines operate farther from Japan—conceivably as far as the South China Sea—Japan may need to resort to local basing in the Philippines or elsewhere.