Seikanron is the insistence of the members of the "Rusu-seifu" on making Korea open to the world by military power (Rusu-seifu means the government while heads of government are away: the heads of Rusu-seifu were Takamori SAIGO, Taisuke ITAGAKI, Shinpei ETO, Shojiro GOTO, and Taneomi SOEJIMA). However, it is said that the insistence of Saigo, who was the central figure of Seikanron, was not on dispatching military but on his himself going there as a Japanese official diplomatic delegation and on asking Korea to open its country to the world (this insistence is called 'Kenkanron' [the insistence on sending delegations to Korea).
They insisted on sending military to Korea on ground that some scholars of Kokugaku (the study of Japanese classical literature) and Mito-gaku (the scholarship and academic traditions that arose in the Mito Domain), and Shoin YOSHIDA said that ancient Japan had hegemony over Korean peninsula according to "Kojiki" (The Record of Ancient Matters) and "Nihon-shoki" (Chronicles of Japan). In addition, this idea was brought into the political insistence of the Sonno-joi movement (the movement advocating reverence for an emperor and the expulsion of foreigners).
After the Meiji Restoration, the Meiji government noticed Korea to establish a new government and negotiated to have diplomatic relations, but Korea rejected them because the format of diplomatic papers was different from the one of Edo period. In Korea, the King's father Daewongun governed the country instead of the King at that time, adopting the policy of national isolation and expulsion of foreigners, and Korean people was in high spirits. In March 1870, the Meiji government sent Hakubo SATA and Shigeru MORIYAMA to Korea, but SATA petitioned the government to conquer Korea by military force because he resented the attitude of Korea. In September, the government sent Gaimu-shojo (Junior Secretary of the Ministry of Foreign Affairs) Koki YOSHIOKA to Busan, and in February 1872, they appointed Yoshiakira SO as Gaimu-taijo (Senior Secretary of the Ministry of Foreign Affairs), and then, they sent Gaimu-taijo Yoshimoto HANABUSA to Korea in September. The movement of anti-Japanese became more active in 1873 instead of accepting the delegates from Japan, and then Korean officials led a boycott of Japanese goods and people in April and May. Therefore, the dispute of Seikanron became heated in Japan.
In June 1873, the problem of diplomacy with Korea was highlighted at the cabinet meeting again after Shigeru MORIYAMA was back to Japan. Sangi (the Councilor) Taisuke ITAGAKI insisted that Japan dispatch the military for protecting Japanese residents in Korea, whereas Takamori SAIGO opposed to send the military and insisted that he himself go to Korea as an ambassador. Shojiro GOTO, Shinpei ETO agreed with SAIGO. The Meiji government once decided to send Takamori SAIGO as an ambassador to Korea in August 1873, but Toshimichi OKUBO, Tomomi IWAKURA, Takayoshi KIDO and other members of the Iwakura Mission who returned Japan in September 1873 opposed it because it was too early in their opinion, and the government finally decided to suspend to send Saigo to Korea. The Grand Minister SANJO fell ill because the situation became uncontrollable to him. In consequence, Saigo, Itagaki and others who supported Seikanron went into opposition (this incident is called the "Seikanron Coup" or the "Coup of 1873"), and they became leaders of the revolt by Shizoku (family or person with samurai ancestors) from Saga War in 1874 to Satsuma Rebellion or the Freedom and People's Right Movement.