20th century Soon after the end of the
Pacific War in 1945 with Japan accepting the
Potsdam Declaration, the
Imperial Japanese Army and
Imperial Japanese Navy were dismantled by the orders of
Supreme Commander for the Allied Powers (SCAP). Both were replaced by the
United States Armed Forces occupation force, which assumed responsibility for the external defense of Japan.
Douglas MacArthur insisted that Japan have no military that could be used to settle international disputes or even for its own self defense. Accordingly, during the development of the
Japan Constitution in 1946,
Article 9 was added stating "the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes." "In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized." It is believed that the Special
Diet Session leader
Hitoshi Ashida added the clause "In order to accomplish the aim of the preceding paragraph" in the middle of Article 9. The intent of this phrasing was to allow for the creation of
military forces in Japan which would be for the defense of Japan, and not for settling international disputes. Then Prime Minister
Shigeru Yoshida accepted this wording and was able to convince the US to allow Japan to operate "
self defense" forces. Under the terms of the
Treaty of Mutual Cooperation and Security between the United States and Japan, United States forces stationed in Japan were to deal with external aggression against Japan while Japanese forces, both ground and maritime, would deal with internal threats and natural disasters. Only after the outbreak of the
Korean War did MacArthur authorise Prime Minister Shigeru Yoshida to establish a 75,000 strong
National Police Reserve. The next expansion came in 1952, when as a compromise in the face of U.S. calls to build up an army of 350,000, the National Police Reserve was re-titled the National Safety Force and expanded to 110,000. In 1954, Prime Minister Yoshida impelled the Diet to accept the Defence Agency Establishment and the Self-Defence Force Laws, which explicitly authorized the forces to "defend Japan against direct and indirect aggression, and when necessary to maintain public order." On July 1, 1954, the National Security Board was reorganized as the Defense Agency, and the National Security Force was reorganized afterwards as the Japan Ground Self-Defense Force (
Army), the
Japan Maritime Self-Defense Force (
Navy) and the
Japan Air Self-Defense Force (
Air Force), with General
Keizō Hayashi appointed as the first Chairman of Joint Staff Council—professional head of the three branches. The enabling legislation for this was the 1954 Self-Defense Forces Act [Act No. 165 of 1954]. That year the actual strength of the Ground, Maritime and Air Self-Defence Forces reached 146,285, armed mainly with U.S. World War II vintage equipment. At least up until the 1970s, the Ground SDF was not built up to the point required to defeat an invasion attempt from the north – informed officials estimated that while ammunition provisions were officially said to be enough to last for two months, in actuality it would be used up in a week or less. During the 1970s, the Japan Ground Self-Defense Force possessed a dubious ability to hold off a Soviet invasion of
Hokkaido.
Zbigniew Brzezinski observed in 1972 that it seemed optimized to fight "a Soviet invasion conducted on American patterns of a quarter of a century ago." Three years later in 1975, Osamu Kaihara, the former secretary of the National Defence Council, was reported in
U.S. News & World Report that the SDF would have been totally ineffective in any Soviet attack, as the Ground SDF could only fight as an army for three to four days. While the force is now an efficient army of around 150,000, its apparent importance had, until recently, seemingly declined with the end of the
Cold War, and attempts to reorient the forces as a whole to new post Cold War missions have been tangled in a series of internal political disputes.
21st century On March 27, 2004, the
Japan Defense Agency activated the
Special Operations Group with the mandate under the JGSDF as its
Counter-terrorist unit. In 2015, the
Japanese Diet passed a law that allowed for the reinterpretation of Article 9 of the constitution. JSDF personnel train with the American forces in amphibious assault units designed to take outlying islands. Japan activated its first marine unit since World War II on April 7, 2018. The marines of the
Amphibious Rapid Deployment Brigade are trained to counter invaders from occupying Japanese islands along the edge of the East China Sea. British troops of the
Honourable Artillery Company (HAC) exercised together for the first time with Japanese GSDF soldiers in
Oyama, Shizuoka prefecture on 2 October 2018. The purpose was to improve their strategic partnership and security cooperation. Speaking about tensions regarding
North Korea, Lieutenant General
Patrick Sanders said that Japan "won't have to fight alone." The
JGSDF and the
Indian Army conducted their first joint military exercise in the Indian state of
Mizoram from 27 October to 18 November 2018. It primarily consisted of anti-terror drills and improving bilateral cooperation with 60 Japanese and Indian officers. In March 2019, the Ministry of Defense established its first regional cyber protection unit in the Western Army of the Japan Ground Self-Defense Force (JGSDF) to safeguard defense communications from cyber attacks, such as for personnel deployed on remote islands with no established secure lines. The Japanese government approved the first ever JSDF dispatch to a peacekeeping operation that is not led by the
United Nations in 2019. JGSDF officers monitored the cease-fire between Israel and Egypt at the Multinational Force and Observers command in the
Sinai Peninsula from 19 April until 30 November 2019. From September to the end of November 2021, the GSDF conducted nationwide drills with all units including 100,000 personnel, 20,000 vehicles, 120 aircraft and the
JMSDF and
JASDF as well as a
U.S. Army landing ship. == Current deployment ==