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Japan Maritime Self-Defense Force

The , or JMSDF, is the maritime branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. It was formed following the dissolution of the Imperial Japanese Navy after World War II.

The JMSDF is a large fleet, largely consisting of destroyers, and has significant blue-water operating capabilities. The force is based strictly on defensive armament, largely lacking the offensive weapons typically handled by naval forces of equivalent size. Currently, its main tasks are to maintain control of the nation's sea lanes and to patrol territorial waters. It has also stepped up its participation in UN-led peacekeeping operations (PKOs) and Maritime Interdiction Operations (MIOs).

The JMSDF has an official strength of 46,000 personnel (currently around 45,800 personnel), operating 119 major warships, including twenty submarines, fifty-three destroyers and frigates, twenty-nine mine warfare ships, nine patrol craft and nine amphibious ships (total displacement of approx. 432,000 tons). It also has 179 fixed-wing aircraft and 135 helicopters. Most of these aircraft are used in antisubmarine and mine warfare operations.

The ship prefix for JMSDF ships is JDS (Japanese Defense Ship) for all ships commissioned before 2008. Ships commissioned on or after 2008 will use the prefix JS (Japanese Ship) to reflect the upgrading of the Japanese Defense Agency to the Ministry of Defense.



Japan has a long history of naval interaction with the Asian continent, involving transportation of troops, starting at least with the beginning of the Kofun period in the 3rd century. Following the attempts at Mongol invasions of Japan by Kubilai Khan in 1274 and 1281, Japanese wakō became very active in plundering the coast of the Chinese Empire.

Japan undertook major naval building efforts in the 16th century, during the Warring States period, when feudal rulers vying for supremacy built vast coastal navies of several hundred ships. Around that time, Japan may have developed one of the world's first ironclad warships, when Oda Nobunaga (a Japanese daimyo) had six iron-covered Oatakebune made in 1576.

In 1588, Toyotomi Hideyoshi issued a ban on Wakō piracy; the pirates then became vassals of Hideyoshi and comprised the naval force used in the Japanese invasion of Korea.

Japan built her first large ocean-going warships in the beginning of the 17th century, following contact with European countries during the Nanban trade period. In 1613, the Daimyo of Sendai, in agreement with the Tokugawa Bakufu, built the Date Maru. This 500 ton galleon-type ship transported the Japanese embassy of Hasekura Tsunenaga to the Americas and Europe. From 1604 onwards, about 350 Red seal ships, usually armed and incorporating European technology, were also commissioned by the Bakufu, mainly for Southeast Asian trade.

Creation of the Imperial Japanese Navy

From 1868, the restored Meiji Emperor continued with reforms to industrialize and militarize Japan to prevent the United States and European powers from overwhelming her. On 17 January 1868, the Ministry of Military Affairs was established, with Iwakura Tomomi, Shimazu Tadayoshi and Prince Komatsu-no-miya Akihito as the First Secretaries.

On 26 March 1868, the first Naval Review was held in Japan (in Osaka Bay), with 6 ships from the private domainal navies of Saga, Chōshū, Satsuma, Kurume, Kumamoto and Hiroshima participating. The total tonnage of these ships was 2252 tons, far smaller than the tonnage of the single foreign vessel (from the French Navy) that also participated. The following year, in July 1869, the Imperial Japanese Navy was formally established, two months after the last military engagement of the Boshin War. In July 1869, the private navies of the Japanese nobles were abolished, and their 11 ships were added to the 7 surviving vessels of the defunct Tokugawa bakufu navy, including the Kankō Maru, Japan's first steam warship. This formed the core of the new Imperial Japanese Navy.

A 1872 edict officially separated the Japanese Navy from the Japanese Army. Politicians like Enomoto Takeaki set out to use the Navy to expand to the islands south of Japan in similar fashion to the Army's northern and western expansion. The Navy sought to upgrade its fleet to a blue water navy and used cruises to expand the Japanese consciousness on the southern islands. Enomoto's policies helped the Navy expand and incorporate many different islands into the Japanese Empire, including Iwo Jima in 1889. The navy continued to expand and incorporate political influence throughout the early twentieth century.

Formation of the Japanese Maritime Self-Defense Force

Following the defeat of Japan during World War II, the Imperial Japanese Navy was dissolved by the Potsdam Declaration acceptance. Ships were decommissioned and scrapped or used as targets for Allied military exercises and weapon tests, whilst personnel were demobilised.

Japan's 1947 Constitution was drawn up after the conclusion of the war, Article 9 specifying that "The Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as a means of settling international disputes." The long-standing view in Japan is that this article allows for military forces to be kept for the purposes of self-defense. Due to Cold War pressures, the United States was also happy for Japan to provide part of its own defense, rather than have it fully rely on American forces.

The JMSDF was formally created as the naval branch of the Japanese Self-Defense Force (JSDF) following the passage of the 1954 Self-Defense Forces Law.

The first ships in the JMSDF were former US Navy destroyers, transferred to Japanese control in 1954. In 1956, the JMSDF received its first domestically produced destroyer since World War II, the Harukaze. Due to the Cold War threat posed by the Soviet Navy's sizeable and powerful submarine fleet, the JMSDF was primarily tasked with an anti-submarine role.

Post Cold War

Following the end of the Cold War, the role of the JMSDF has vastly changed. Starting with a mission to Cambodia in 1993, it has been active in a number of United Nations-led peace keeping operations throughout Asia. In 1993, it commissioned its first Aegis destroyer, the DD173 Kongō. It has also been active in joint naval exercises with other countries, such as the United States. The JMSDF has dispatched a number of its destroyers on a rotating schedule to the Indian Ocean in an escort role for allied vessels as part of the US-led Operation Enduring Freedom.

Following an increase in tensions with North Korea following the 1993 test of the Nodong-1 missile and the 1998 test of the Taepodong-1 missile over northern Japan, the JMSDF has also stepped up its role in theatre air defense of Japan. A ship-based anti-ballistic missile system was successfully test-fired on December 18, 2007 and has been installed on Japan's Aegis-class destroyers. The JMSDF has also been active in preventing North Korean infiltrators from reaching Japan engaging and sinking a North Korean spyship in 2001.

Capabilities and recent developments

Japan has the 6th largest Exclusive Economic Zone (EEZ) in world, and the JMSDF is responsible for protecting this large area. As an island nation, dependent on maritime trade for the majority of its resources, including food and raw materials, maritime operations are a very important aspect of Japanese defense policy.

The JMSDF is known in particular for its anti-submarine and mine-sweeping capability. Defense planners believe the most effective approach to combating submarines entails mobilizing all available weapons, including surface combatants, submarines, aircraft and helicopters. Historically the ASDF has been relied upon to provide air cover at sea, a role that is subordinate to ASDF's primary mission of air defense of the home islands. Extended patrols over sea lanes are beyond the ASDF's current capabilities.

The fleet's capacity to provide ship-based anti-air protection is limited by the absence of aircraft carriers, though its Aegis-equipped destroyers provide a formidable capability in air-air warfare. The fleet is also short of underway replenishment ships and generally deficient in all areas of logistic support. These weaknesses seriously compromise the ability of the MSDF to fulfill its mission and operate independently of the United States Air Force and the United States Seventh Fleet. However, these capabilities are force multipliers, allowing force projection of Japan's sizeable destroyer and frigate force far from home waters, and acquiring them is contentious considering Japan's "passive" defence policy.

In August 2003, a new "helicopter destroyer" class was ordered, the Hyūga class helicopter destroyer. The size and features of the ship, including a full length flight deck, will result in it being classifed as either an amphibious assault ship, or helicopter carrier by Lloyd's Register, similar to . It has been widely disputed if a carrier of any sort would be technically prohibited by Article 9 of the Japanese Constitution, as carriers are generally considered offensive weapons. In an April 1988 Diet budget session, then Defense Agency chief Tsutomu Kawara said that "The Self-Defense Forces are not allowed to possess ICBMs (intercontinental ballistic missiles), strategic bombers, or attack aircraft carriers."

Until the 1970s in the US Navy, large-scale flattops had been categorized as "attack aircraft carriers" and small flattops as "anti-submarine aircraft carriers." Since helicopter carriers have little organic attack capability and primarily fulfill roles including logistics and transport, the government continues to argue that the prohibition does not extend to the new ship.

International Activities

Mission in the Indian Ocean

Destroyers and combat support ships of Japan Maritime Self-Defense Force were dispatched to the Indian Ocean from 2001 to 2008 to participate in OEF-MIO (Operation Enduring Freedom-Maritime Interdiction Operation). Their mission is to prevent the marine transportation of illegal weapons and ammunition, and the drugs which fund terrorist activity. Since 2004, the JMSDF has provided ships of foreign forces with fuel for their ships and ship-based helicopters, as well as fresh water.

This was the third time Japanese military vessels had been dispatched overseas since World War II, following the deployments of a mine-sweeping units during the Korean War and the Gulf War. The law enabling the mission expired on November 2 2007, and the operation was temporarily cancelled due to a veto of a new bill authorising the mission by the opposition-controlled upper chamber of the Japanese Diet. A new law was subsequently passed when the lower chamber overruled the veto, and the mission was resumed.

Military exercises and exchanges

The JMSDF and U.S. Navy frequently carry out joint exercises. The JMSDF participates in RIMPAC, the annual multi-national military exercise in Hawaii that has been hosted by US Navy since 1980. The JMSDF dispatched a ship to Vladivostok harbour in July in 1996 to participate in the Russian Navy's 300th anniversary naval review. Vradimir Vinogradov came by ship to Tokyo harbor in June in 1997 in the Russian Federation. The JMSDF has also conducted joint naval exercises with the Indian navy.

  • RIMPAC: Japan Maritime Self-Defense Force participates in RIMPAC after 1980.
  • Pacific Shield(PSI): Japan Maritime Self-Defense Force participates in Pacific Shield after 2004, and in 2007 the Japan Maritime Self-Defense Force hosted the exercise.
  • Pacific Reach: Japan Maritime Self-Defense Force has participated in the biannual submarine rescue exercise since 2000. In 2002, the Japan Maritime Self-Defense Force hosted the exercise.
  • Navy to Navy Talks: Japan Maritime Self-Defense Force holds regular naval conferences with its counterparts of Indonesia, Malaysia, the United Kingdom, and United States.
  • Aegis Ballistic Missile Defense FTM: Japan Maritime Self-Defense Force has participated in the FTM after FTM-10. Japan Maritime Self-Defense Force carried out JFTM-1 in December, 2007.

Ranks of the Japan Maritime Self-Defense Force

The following details the officer ranks of the JMSDF, showing the Japanese rank, the English translation and the NATO equivalent.

Commissioned Officers

Japanese Rank (in Japanese) Japanese Rank (in English) NATO Code
幕僚長たる海将 (Bakuryou-chou taru kaishou) Admiral OF-9
海将 (Kaishou) Vice-Admiral OF-8
海将補 (Kaishou-ho) Rear-Admiral OF-7
1等海佐 (Ittou Kaisa) Captain OF-5
2等海佐 (Nitou Kaisa) Commander OF-4
3等海佐 (Santou Kaisa) Lieutenant Commander OF-3
1等海尉 (Ittou Kaii) Lieutenant OF-2
2等海尉 (Nitou Kaii) Lieutenant Junior Grade OF-1
3等海尉 (Santou Kaii) Ensign OF-1

Warrant officers

准海尉 (Jun Kaii) Warrant Officer OR-9

Non-Commissioned Officers

海曹長 (Kaisou chou) Chief Petty Officer OR-8
1等海曹 (Ittou Kasou) Petty Officer 1st Class OR-7
2等海曹 (Nitou Kaisou) Petty Officer 2nd Class OR-6
3等海曹 (Santou Kaisou) Petty Officer 3rd Class OR-5


海士長 (Kaishichou) Leading Seaman OR-4
1等海士 (Ittou Kaishi) Seaman OR-3
2等海士 (Nitou Kaishi) Seaman Apprentice OR-2
3等海士 (Santou Kaishi) Seaman Recruit OR-1


The JMSDF is commanded by the Chief of the Maritime Staff. Its structure consists of the Maritime Staff Office, the Self-Defense Fleet, five regional district commands, the air-training squadron and various support units, such as hospitals and schools. The Maritime Staff Office, located in Tokyo, serves the Chief of Staff in commanding and supervising the force.

The Self-Defense Fleet, headquartered at Yokosuka, consists of the JMSDF's military shipping. It is composed of four Escort Flotillas (based in Yokosuka, Sasebo, Maizuru and Kure), the Fleet Air Force headquartered at Atsugi, two Submarine Flotillas based at Kure and Yokosuka, two Mine-sweeping Flotillas based at Kure and Yokosuka and the Fleet Training Command at Yokosuka.

The JMSDF is planning to reorganize the respective Escort Flotillas into a DDH group and DDG group, enabling faster overseas deployments.

  • JMSDF Chief of Staff / Maritime Staff Office
    • Self Defense Fleet (Mobile Flotilla)
      • Fleet Escort Force
        • Escort Flotilla 1 (Yokosuka)
          • Escort Squadron 1 (DDG,DDH,DDx2)
          • Escort Squadron 5 (DDG,DDx3)
        • Escort Flotilla 2 (Sasebo)
          • Escort Squadron 2 (DDG,DDH,DDx2)
          • Escort Squadron 6 (DDG,DDx3)
        • Escort Flotilla 3 (Maizuru)
          • Escort Squadron 3 (DDG,DDH,DDx2)
          • Escort Squadron 7 (DDG,DDx3)
        • Escort Flotilla 4 (Kure)
          • Escort Squadron 4 (DDG,DDH,DDx2)
          • Escort Squadron 8 (DDG,DDx3)
        • Fleet Training Command
        • 1st Replenishment Squadron
        • 1st Transportation Squadron
      • Fleet Air Force
      • Fleet Submarine Force
        • Submarine Flotilla 1
          • Submarine Squadron 1
          • Submarine Squadron 3
          • Submarine Squadron 5
        • Submarine Flotilla 2
          • Submarine Squadron 2
          • Submarine Squadron 4
        • Submarine Training Command
      • Mine Warfare Force
      • Fleet Research & Development Command
      • Fleet Intelligence Command
      • Oceanographic Command
    • Air Training Command
      • Shimousa Air Training Group (P-3C YS-11TA UH-60J)
      • Tokusima Air Training Group (TC-90 UC-90 UH-60J)
      • Ozuki Air Training Group (T-5 UH-60J)
    • Maritime Material Command
      • Ship Supply Depot
      • Air Supply Depot
    • Training Squadron
    • Communication Command
    • Criminal Investigation Command
    • JMSDF Staff College
    • Maritime Officer Candidate School
    • 1st Service School
    • 2nd Service School
    • 3rd Service School
    • 4th Service School
    • Yokosuka District Force
    • Kure District Force
    • Sasebo District Force
    • Maizuru District Force
    • Ominato District Force

Escort Forces

Each Escort force is formed as an 8-8 fleet of 8 destroyers and 8 on-board helicopters, a modification of the old Japanese Navy fleet layouts of 8 battleships and 8 cruisers. Each force is composed of one helicopter destroyer (DDH) acting as a command ship, two guided-missile destroyers (DDG) and 5 standard or ASW destroyers (DD).

  • First Escort Force - Yokosuka
  • Second Escort Force - Sasebo
  • Third Escort Force - Maizuru
  • Fourth Escort Force - Kure

District Forces

Five district units act in concert with the fleet to guard the waters of their jurisdictions and provide shore-based support. Each district is home to a major JMSDF base and its supporting troops and staff. Furthermore, each district is home to one to two regional escort squadrons, composed of two to three destroyers or destroyer escorts (DE). The destroyers tend to be of older classes, mainly former escort force ships. The destroyer escorts, on the other hand, tend to be purpose built vessels. Each district also has a number of minesweeping ships.

Fleet Air Force

The Fleet Air Force is tasked with patrol, ASW and rescue tasks. It is composed primarily of 7 aviation groups. Prominent bases are maintained at Kanoya, Hachinohe, Atsugi, Naha, Tateyama, Oomura and Iwakuni. The Fleet Air Force is built up mainly with patrol aircraft such as the Lockheed P-3 Orion, rescue aircraft such as the US-1A and helicopters such as the SH-60J. In the JMSDF, helicopters deployed to each escort force are actually members of Fleet Air Force squadrons based on land.

Special Forces

Special Forces units consist of the following:

In Japanese, known as "特別警備隊(Tokubetsu keibi tai)".

In Japanese, known as "護衛艦付き立ち入り検査隊(Goeikan-zuki Tachi'iri Kensa Tai)".

Recruitment and Training

JMSDF recruits receive three months of basic training followed by courses in patrol, gunnery, mine sweeping, convoy operations and maritime transportation. Flight students, all upper-secondary school graduates, enter a two-year course. Officer candidate schools offer six-month courses to qualified enlisted personnel and those who have completed flight school. Graduates of four-year universities, the four-year National Defense Academy, and particularly outstanding enlisted personnel undergo a one-year officer course at the Officer Candidate School at Etajima (site of the former Imperial Naval Academy). The JMSDF also operates a staff college in Tokyo for senior officers.

The large volume of coastal commercial fishing and maritime traffic around Japan limits in-service sea training, especially in the relatively shallow waters required for mine laying, mine sweeping and submarine rescue practice. Training days are scheduled around slack fishing seasons in winter and summer—providing about ten days during the year. The JMSDF maintains two oceangoing training ships and conducted annual long-distance on-the-job training for graduates of the one-year officer candidate school.


Japan's Ground Self-Defense Force was created by the U.S. Army and dropped its association with the Imperial Japanese Army. However, the JMSDF has emphasized the history and traditions of the Imperial Japanese Navy, using the same martial songs, naval flags, signs and technical terms as the Imperial Japanese Navy. For example, the official flag of the JMSDF is the same that was used by the Imperial Japanese Navy, and the tradition of eating curry every Friday originated with the Imperial Japanese Navy.

Five Reflections

  1. Hast thou not gone against sincerity
  2. Hast thou not felt ashamed of thy words and deeds
  3. Hast thou not lacked vigor
  4. Hast thou exerted all possible efforts
  5. Hast thou not become slothful

The JMSDF uses the Five Reflections (Gosei) for self reflection in daily life, which were originally devised by Vice Admiral Hajime Matsushita (Chief of Imperial Japanese Navy, Naval Academy). Every evening cadets are expected to meditate using the Five Reflections. This has been translated into English and has been discussed at the United States Naval Academy as well.


Guided Missile Destroyers (DDG)

Destroyers (DD)

Helicopter Destroyers (DDH)

Destroyer Escorts (DE)

Submarines (SS)

Amphibious Forces


  • Yaeyama class ocean minesweepers (3 in service)
  • Uwajima class MSC (coastal) (9 in service)
  • Hatsushima Class MSC (coastal) (4 in service)
  • Sugashima Class (coastal) (12 in service)


  • Hayabusa class (PG:Guided Missile Patrol Boat) (6 in service)
  • 1 go class (PG:Guided Missile Patrol Boat) (3 in service)


Future vessels


Aircraft Origin Type Versions In service Notes AgustaWestland EH101

Minesweeping helicopter MCH-101 2 12 more on order.
Replacing the MH-53E and S-61A. Beechcraft King Air Trainer
Aerial survey TC-90
UC-90 31 Fuji T-5 Trainer 35 Learjet 35 Utility aircraft U-36A 4 Lockheed P-3 Orion Maritime patrol
EP-3C 80
5 Built by Kawasaki MD Helicopters MD 500 Trainer helicopter OH-6D
OH-6J 5
4 Built by Kawasaki NAMC YS-11 Utility transport YS-11T 10 ShinMaywa US-1 Rescue flying boat US-1A 7 ShinMaywa US-2 Rescue flying boat US-2 1 Sikorsky S-61 Sea King Transport helicopter S-61A 3 SH-60 Seahawk
Naval helicopter SH-60J
SH-60K 103
14 Built by Mitsubishi UH-60 Black Hawk Rescue helicopter UH-60J 19 Built by Mitsubishi Sikorsky S-80 Sea Stallion Minesweeping helicopter MH-53E 10

Future Aircraft

  • The Kawasaki P-1 is the MSDF's next generation patrol aircraft. It is planned to replace the P-3C Orion patrol aircraft already in service, with aircraft due to enter service in 2010. The P-1's maiden flight took place in Gifu airbase (Japan) on September 28, 2007.

See also


External links

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