US Enters the Korean Conflict In 1948 the Korea Peninsula was divided between a Soviet-backed government in the north and an American-backed government in the south. War broke out along the 38th parallel on June 25, 1950. On that day, North Korean troops coordinated an attack at several strategic points along the parallel and headed south toward Seoul. The United Nations Security Council responded to the attack by adopting a resolution that condemned the invasion as a "breach of the peace." Read