Why was the 38th parallel chosen to divide Korea after World War II?

The 38th parallel was chosen by U.S. military planners in August 1945 as a temporary administrative boundary to facilitate the surrender of Japanese forces following World War II. Under this arrangement, Japanese troops north of the line were to surrender to the Soviet Union, while those south of the line were to surrender to the United States.12

While the division was intended to be temporary, historians note that the decision was driven by military expediency and a strategic desire to prevent the Soviet Union from occupying the entire Korean Peninsula. By establishing this line, the United States aimed to ensure that no single power would dominate Korea, effectively halting the Soviet advance south of the 38th parallel. As Cold War tensions intensified, this temporary military demarcation hardened into a permanent political division between the communist regime in the north and the U.S.-oriented government in the south.132