Japan Maritime Self-Defense Force
The Japan Maritime Self-Defense Force, abbreviated JMSDF, also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy after World War II. The JMSDF has a fleet of 164 ships, 346 aircraft and 50,800 personnel.
History
Origin
Following Japan's defeat in World War II, the Imperial Japanese Navy was dissolved by the Potsdam Declaration acceptance. Ships were disarmed, and some of them, such as the battleship, were taken by the Allied Powers as reparations. The remaining ships were used for repatriation of the Japanese soldiers from abroad and also for minesweeping in the area around Japan, initially under the control of the Second Bureau of the Demobilization Ministry. The minesweeping fleet was eventually transferred to the newly formed Maritime Safety Agency, which helped maintain the resources and expertise of the navy.Japan's 1947 Constitution was drawn up after the conclusion of the war, which contained Article 9, which specified 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 prevalent 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.
In 1952, the Safety Security Force was formed within the Maritime Safety Agency, incorporating the minesweeping fleet and other military vessels, mainly destroyers, given by the United States. In 1954, the SSF was separated, and the JMSDF was formally created as the naval branch of the Japan Self-Defense Forces, following the passage of the 1954 Self-Defense Forces Law.
The first ships in the JMSDF were former U.S. Navy destroyers, transferred to Japanese control in 1954. In 1956, the JMSDF received its first domestically produced destroyer since World War II, Harukaze. Due to the Cold War threat posed by the Soviet Navy's sizable 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. In 1991, after international pressure, the JMSDF dispatched four minesweepers, a fleet oiler and a minesweeping tender to the Persian Gulf in the aftermath of the Gulf War, under the name of Operation Gulf Dawn, to clear mines sown by Saddam Hussein's defending forces. Starting with a mission to Cambodia in 1993 when JSDF personnel were supported by JDS Towada, it has been active in a number of UN-led peacekeeping operations throughout Asia.In 1993, the JMSDF commissioned its first Aegis-equipped destroyer,. 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 UN-led Operation Enduring Freedom.
21st century
The JMSDF, along with the Japan Coast Guard, has also been active in preventing North Korean infiltrators from reaching Japan and on 22 December 2001, engaged and sank a North Korean spy ship in the Battle of Amami-Ōshima.In 2002, the JMSDF deployed ships to the Arabian Sea in support of Operation Anaconda during the War in Afghanistan.
In August 2003, a new "helicopter carrier" class was ordered, the. Due to the size and features of the ship, including a full-length flight deck, it was classified as a helicopter carrier by Lloyd's Register — similar to the United Kingdom's. The Self-Defense Forces are not allowed to possess ICBMs, strategic bombers, or "attack aircraft carriers". However, according to the Japanese government's definition, "attack aircraft carriers" refer specifically to carriers designed solely for nuclear bombers to conduct nuclear strikes. Aircraft carriers equipped with helicopters, conventional fighter jets or attack aircraft—whether they are small light carriers or large nuclear-powered carriers—are not considered illegal.
With 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 increased its efforts in air defense. A ship-based anti-ballistic missile system was successfully test-fired on 18 December 2007 and has been installed on Japan's Aegis-equipped destroyers.
In November 2009, the JMSDF announced plans for a larger "helicopter carrier", the. In 2025, these vessels were re-classified as "multi-role aircraft-carrying cruisers" as part of their conversion to operate F-35B V/STOL fighters. This made them de facto aircraft carriers. To avoid controversy, the ruling parties initially classified the vessels "multi-purpose operation destroyers" and then, in 2025, as "multi-role aircraft-carrying cruisers". The first of these ships was laid down in 2012 and was launched on 6 August 2013. Two vessels of the class were in service as of 2025.
The submarine fleet of the JMSDF consists of some of the most technologically advanced diesel-electric submarines in the world. This is due to careful defense planning in which the submarines are routinely retired from service ahead of schedule and replaced by more advanced models. In 2010 it was announced that the Japanese submarine fleet would be increased in size for the first time in 36 years.
After a meeting between the Japanese Foreign Minister Fumio Kishida and U.S. Ambassador to Japan Caroline Kennedy on 4 March 2014, the Japanese Defense Ministry and U.S. Department of Defense announced they would hold studies for the joint development of the littoral vessel under the bilateral Mutual Defense Assistance Agreement. The vessel is planned to be a high-speed trimaran designed for operations in shallow coastal waters capable of carrying helicopters, possibly a lighter variant of the American littoral combat ship.
The study was conducted in response to the growth of the Chinese People's Liberation Army Navy and budgetary issues with the U.S. military that may affect their ability to operate in the Pacific. The J-LCS would be used to intervene during Chinese ship incursions near the Senkaku Islands and other contested areas in the East China Sea, and possibly counter similar Chinese vessels like the Type 056 corvette and Type 022 missile boat. A J-LCS with an enlarged hull could operate the SH-60K anti-submarine helicopter or the MCH-101 airborne mine countermeasures helicopter.
On May 1, 2017, was dispatched to protect a U.S. Navy supply vessel in the Pacific. This was the first time the JMSDF was used to defend allied vessels since the 2016 amendment to the Japanese Constitution.
Japan christened the long, JS Ōryū submarine on October 4, 2018. It is Japan's first submarine powered by lithium-ion batteries and was developed by Mitsubishi Heavy Industries. It was commissioned in March 2020.
Japan and the United States conducted the biggest military exercise around Japan in the biennial Keen Sword from 29 October to 2 November 2018. It included a total of 57,000 sailors, marines and airmen. 47,000 service members were from the JSDF and 10,000 from the U.S. Armed Forces. A naval supply ship and a frigate of the Royal Canadian Navy also participated. There were simulations of air combat, ballistic missile defense and amphibious landings.
On 23 May 2019, retired MSDF vice-admiral Toshiyuki Ito stated that Japan requires at least four Izumo-class destroyers to be viable for real naval combat operations. He said "If you only have two vessels, you can only use them for training personnel for taking off and landing operations, so this plan doesn't make sense for MSDF officers, frankly speaking." As aircraft carriers, the Izumo-class destroyers are relatively small, only able to carry approximately 10 F-35Bs, which Ito argued were too few to provide effective air defense.
In 2019, the National Diet of Japan approved the order of 42 STOVL Lockheed Martin F-35 Lightning II aircraft in addition to 135 F-35A model conventional takeoff and landing fighters for the Japan Air Self-Defense Force to operate from their land bases; the F-35B is same model aircraft that the US Marines operate from US Navy aircraft carriers and amphibious assault ships, the US Marines also plan to fly from the Japanese Izumo class after the STOVL modifications and refit.
On October 14, 2020, the 3,000-ton submarine was unveiled. This is the first vessel of the Taigei class and the 22nd submarine vessel of the JMSDF. The Taigei entered service in 2022, and the second ship of the class, Hakugei, was commissioned in 2023.
File:JS Maya.jpg|thumb|Aegis guided-missile destroyer destroyer JS Maya
On 30 June 2022, the Japan Ministry of Defense announced the construction of 12 offshore patrol vessels by Japan Marine United Corporation for the Japan Maritime Self-Defense Force at a cost of ¥ 9 billion per ship. The purpose of this OPV program is to provide enhanced maritime security, particularly around the southwestern Ryukyu Islands, including the disputed Senkaku/Diaoyu Islands in the East China Sea, by boosting JMSDF patrol activities in the region. These vessels are highly automated and configurable to meet a wide range of missions involving "enhanced steady-state intelligence, surveillance, and reconnaissance in the waters around Japan". Under the contract, JMU is charged with delivering the 12 vessels to the JMSDF from fiscal year 2023, which starts on April 1, 2023.
On August 31, 2022, the Japan Ministry of Defense announced that JMSDF will operate two "Aegis system equipped ships" to replace the earlier plan of Aegis Ashore installations, commissioning one by the end of fiscal year 2027, and the other by the end of FY2028. The budget for design and other related expenses are to be submitted in the form of "item requests", without specific amounts, and the initial procurement of the lead items are expected to clear legislation by FY2023. Construction is to begin in the following year of FY2024. At 20,000 tons each, both vessels will be the largest surface combatant warships operated by the JMSDF, and according to Popular Mechanics, they will "arguably the largest deployable surface warships in the world".
On 16 November 2022, the guided-missile destroyer fired an SM-3 Block IIA missile, successfully intercepting the target outside the atmosphere in the first launch of the missile from a Japanese warship. On 18 November 2022, the likewise fired an SM-3 Block IB missile with a successful hit outside the atmosphere. Both test firings were conducted at the Pacific Missile Range Facility on Kauai Island, Hawaii, in cooperation with the U.S. Navy and U.S. Missile Defense Agency. This was the first time the two ships conducted SM-3 firings in the same time period, and the tests validated the ballistic missile defense capabilities of Japan's newest s.
On 16 December 2022, Second Kishida Reshuffled Cabinet approved a trio of defense-related policy documents, including its new National Security Strategy, the strategic guideline document for the Japanese government's policies regarding diplomacy, defense, and economic security for the next decade. Based on the NSS, the National Defense Strategy outlined Japan's defense policy goals and the means to achieve them while the Defense Buildup Program outlined the scale of the introduction of specific defense equipment within the budgetary objectives. According to the Defense Buildup Program, the Japan Maritime Self-Defense Force will increase the number of Aegis-equipped guided-missile destroyers from the current eight to ten, as well as two Aegis system-equipped vessels to be deployed in ballistic missile defense operations. By the end of the decade, the JMSDF will operate 12 ships equipped with Aegis Weapon System and likewise plans to replace its fleet of older, less capable destroyers and destroyer escorts with s.