Why were North Korea and South Korea divided after World War II?

Following the surrender of Japan at the end of World War II in 1945, the Korean Peninsula was divided along the 38th parallel as a temporary administrative measure.123

The division was primarily a military arrangement to facilitate the surrender of Japanese forces: those north of the line surrendered to the Soviet Union, while those to the south surrendered to the United States. U.S. policy aimed to prevent any single power from dominating the peninsula, and the division served to check Soviet expansion.12

Although intended to be temporary, the division hardened into a permanent political split as Cold War tensions intensified. Efforts to establish a unified government through a joint commission failed, leading the U.S. to involve the United Nations. By 1948, two separate regimes were established: the Republic of Korea in the south and the Democratic People’s Republic of Korea in the north. This division was further entrenched by the Korean War, which concluded with an armistice rather than a peace treaty, leaving the two nations technically at war.2345