Here's What You Need to Know: Tokyo is developing a modest capability to respond to incursions on its many vulnerable islands.

Seventy-five years ago, the sight of 300 Japanese marines storming rolling onto a Queensland beach in hulking tracked amphibious vehicles would have heralded a catastrophic setback to Australia’s national security.

But obviously, the world has changed quite a bit since World War II. The soldiers from Japan’s Amphibious Rapid Deployment Brigade (ARB) were not invaders, but participants in the international 2019 Talisman Sabre exercise held biennially on Australian soil.

The scars from World War II, however, explain why post-war Japan—a nation consisting of 6,852 islands—has not had a dedicated amphibious force until 2018.

In the 1930s, the Imperial Japanese Navy began training Special Naval Landing Forces principally at naval bases in Kure, Maizuru, Sasebo and Yokosuka. Initially non-standard in organization, by 1941 there were sixteen battalion-sized SNLF regiments that would spearhead Japanese amphibious assaults in the Philippines, the Netherland East Indies, the American Aleutian Islands of Kiska and Attu, and New Guinea. 

Though the SNLF included some paratrooper and tank units, it was primarily a light infantry force, lacking the mechanized landing craft integral to U.S. Marine Corps. The force’s fearsome reputation was furthered in the massacres of surrendered enemies and by its tendency to fight to the last man in defensive actions such as the bloody battle of Tarawa in 1943.

After the war, Japanese leaders perceived amphibious warfare as fundamentally aggressive, and thus inappropriate for Japan’s self-defense forces and pacifistic constitution. When it came to conflicts over distant islands, the JSDF developed the concept of “Maritime Operational Transport”—rushing troops to those islands before the enemy forces arrived.

But tension between Tokyo and Beijing have intensified in the twenty-first century—most prominently over the Senkaku/Diaoyu islands (the first name is Japanese, the latter Chinese), tiny specks of land over 200 miles away from both mainland China and major Japanese islands.

More ominously, some Chinese scholars have argued that the more populated Nansei/Ryukyu island belt in southwestern Japan—which includes the Okinawa prefecture and is the site of a major U.S. military base—also rightfully belongs to China.

Concerns that Beijing might seize outlying islands finally led in 2018 to the formation of the 2,100-man Amphibious Rapid Response Brigade (ARDB), based at Sasebo on Kyushu—formed under the ground force’s first unified command.

Though Sasebo once based naval SNLF units, the new brigade is formed from the Ground Self Defense Force’s Western Army Infantry Regiment, an elite 680-man light infantry battalion formed in 2002.

The ARDB now consist of two 800-man Amphibious Rapid Deployment Regiments, with a third currently being formed to boost the unit to 3,000 personnel. Support battalions include units specialized in artillery (with 120-millimeter RT mortars), reconnaissance (operating small inflatable boats), engineering and logistical support.

But the brigade’s key support unit is a Combat Landing Battalion comprising 58 hulking AAV-P7A1 amphibious armored vehicles that can swim marines from ship to shore at eight miles per hour. Resembling the Jawa Sand Crawler in Star Wars, the 32-ton “amtracs” can carry twenty-one troops each—two or three times more than most modern personnel carriers—and bristle with .50 caliber machine guns and grenade launchers. However, amtracs are thinly armored—U.S. Marines lost many in Iraq—and may struggle to negotiate the coral reefs surrounding most of Japan’s southwestern islands.

Japan is also procuring seventeen MV-22B Osprey tilt-rotor aircraft for air insertion on remote islands. The Osprey is expensive and its high accident rates have led to large scale protests by Japanese citizens. However, the type’s ability to combine the vertical takeoff and landing ability of a helicopter with the higher potential range and speed of an airplane are vital attributes given the over 600 miles separating the southwestern-most Japanese islands from Kyushu.

The MSDF chips in the third vital logistical element: three Osumi-class Landing Ship, tanks (LSTs) commissioned between 1998–2003. These 14,000-ton vessels be crammed full with up to a thousand troops, or ten large armored vehicles such as Type 16 Maneuver Combat Vehicles. An internal “well deck” allows each LST to launch two of Japan’s six Landing Craft Air Cushions (LCACs) to ferry troops ashore. Japan is working on modifying the Osumis to embark AAV-P7s and MV-22s.

The Japanese Navy also has around a dozen smaller LCMs (Landing Craft Mechanized), and two 540-ton utility landing craft (LCUs). The Ground Self Defense Force has proposed procuring its own landing ships tanks independent of the Maritime Self Defense Force, and has been window shopping for LST designs, though lacks funding.

The newly-minted brigade rapidly became visible in overseas exercise. On October 2018, fifty ARDB soldiers mounted in four amtracs participated in a counter-terrorism exercise in Luzon, in the Philippines. These were the first Japanese armored vehicles to have landed on foreign soil since World War II—at a place where Japanese tanks had first battled U.S. and Filipino forces.

Then 550 ARDB soldiers with AAVs participated in the 2019 Iron Fist exercise at Camp Pendleton, California, followed in June by the amphibious landing in Australia.

But realistically, what’s the operational concept behind the ARDB?

Certainly, Japan shares with Australia, the Philippines and the United States a concern that China may seize key Pacific islands it could use to interdict maritime traffic. But Japan’s constitution forbids its forces from coming to the aid of allies.

Thus, the ARDB’s purpose remains specific: to rapidly recapture Japan’s southwestern islands should they be occupied by Chinese forces. This remains in the United States and Australia’s interests, as the Japanese island belt effectively constrains PLA Navy operations.

Now, a lone 3,000-man brigade, no matter how capable, is not going to tip the balance in a high-intensity conflict. Thus Mina Pollmann argues in The Diplomat that “By the time the islands are taken over by China, Japan has already lost.” She opines Tokyo should instead shift funding to the Maritime and Air Self Defense forces to prevent Chinese forces from reaching any islands in the first place.

However, this overlooks that the amphibious brigade may deter smaller-scale “grey zone” actions possibly mounted by China’s paramilitary naval militias and coast guard. The ability to rapidly and credibly respond to island seizures could fundamentally alter the risk-reward calculus for such actions.

Furthermore, the brigade’s amphibious capabilities should improve the JSDF’s ability to provide disaster relief to isolated coastal and island communities.

Inevitably, some—particularly in China—will perceive Japan’s resurrected amphibious force as a harbinger of aggression. But realistically, Tokyo is simply developing a modest capability to respond to incursions on its many vulnerable islands.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.

This article first appeared in July 2019.

Image: U.S. Marine Corps photo by Lance Cpl. Amy Phan