Korean reunification selected the 38th parallel as a dividing line. Japanese troops to the North of this line were to surrender to the Soviet Union and troops to the South of this line would surrender to the United States. This was not originally intended to result in a long-lasting partition, but Cold War politics resulted in the establishment of two separate governments in the two zones in 1948 and rising tensions prevented cooperation. The desire of many Koreans for a peaceful unification was dashed when the Korean War broke out in 1950. In June 1950, troops from North Korea invaded South Korea.
Korean War conflicts played more of a role in not deploying them than the threat of a possible nuclear exchange. When Eisenhower succeeded Truman in early 1953 he was similarly cautious about using nuclear weapons in Korea, including for diplomatic purposes to encourage progress in ongoing truce discussions. The administration prepared contingency plans to use them against China, but like Truman, the new president feared doing so would result in Soviet attacks on Japan. The war ended as it began, without U.S. nuclear weapons deployed near battle. There were numerous atrocities and massacres of civilians throughout the Korean war committed by both