Following Japan's defeat in World War II, the Imperial Japanese Navy was dissolved by the Potsdam Declaration acceptance.

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.

[8] The minesweeping fleet was eventually transferred to the newly formed Maritime Safety Agency, which helped maintain the resources and expertise of the navy.

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.

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.

[9] Starting with a mission to Cambodia in 1993 when JSDF personnel were supported by JDS Towada,[9] it has been active in a number of UN-led peacekeeping operations throughout Asia.

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.

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 HMS Ocean.

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.

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.

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 3,000-tonne (3,000-long-ton) littoral combat ship.

[19] 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.

[24] 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.

[25] 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.

These vessels are highly automated and configurable to meet a wide range of missions involving "enhanced steady-state intelligence, surveillance, and reconnaissance (ISR) in the waters around Japan".

As a result of continuing effective defense investment due to Japan's economic development and an end to the Cold War, the JMSDF became the world's fourth largest navy by total tonnage by 2000.

[36] Japan has the eighth largest Exclusive Economic Zone (EEZ) in the world,[37] and the JMSDF is responsible for protecting this large area.

They are also known to operate at least fourteen listening stations all over the country that have ELINT and marine surveillance radar warning systems.

In January 2010, the defense minister ordered the JMSDF to return from the Indian Ocean, fulfilling a government pledge to end the eight-year refueling mission.

Prime Minister Yukio Hatoyama refused to renew the law authorizing the mission, ignoring requests from the American government for continuation.

[41] In May 2010, Japan announced its intention to build a permanent naval base in Djibouti, from which it will conduct operations to protect merchant shipping from Somali pirates.

[48][49][50] On 6 October 2022, five warships from the United States, Japan, and South Korea held a multilateral ballistic missile defense exercise in the Sea of Japan (pictured) as part of the military response to ongoing North Korean intermediate-range ballistic missile tests over the Japanese home islands.

Two additional IBCBMs were subsequently launched on 20 February 2023, with both landing in the Sea of Japan off the east coast of the Korean Peninsula.

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.

[citation needed] Today's JMSDF continues to use the same martial songs, naval flags, signs, and technical terms as the IJN.

[citation needed] The Imperial Japanese Navy first adopted the off-set naval ensign Jyūrokujō-Kyokujitsu-ki (十六条旭日旗) on May 15, 1870, and it was used until the end of World War II in 1945.

[61][62] The old off-set navy flag with the sun and 16 rays was re-adopted as the ensign of the Maritime Self-Defense Force, but it was modified with a brighter red color.

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, minesweeping, and submarine rescue practice.