The Korean War began at dawn on June 25, 1950, with the advance south of the 38th parallel by the North Korean army. It is a classic example of an international civil war. It combined the confrontation within the Korean peninsula over leadership of a united Korean nation, with the struggle for spheres of influence between the United States and the Soviet Union that had begun in the closing stages of the Second World War. It was fought for over three years until the armistice agreement of July 27, 1953, leaving the Korean peninsula deeply scarred and having a profound influence on the Cold War. The Cold War between the East and West had at first been anticipated as being a local event limited to Europe. However, with the Korean War, it became a militarized confrontation. Furthermore, with the formation of the American-led anti-communist military encirclement from Europe to Asia, it also became a global confrontation. Meanwhile, in Asia, the Korean War transformed the division of Korea into a permanent reality. It made it impossible for China to think of "liberating" Taiwan by military means. And it created a situation of confrontation between the United States and China that was to continue for twenty years. The United States' decision to intervene in Vietnam was also heavily influenced by the Korean War.
This is a revised and updated version of the following articles: "Chosen sensa no shogeki," Gunjishigaku 36, no. 3-4 (2001), 33-47; "The Impact of the Korean War on Japan," Keio Journal of Politics 13 (2008): 1-9.