According to Cummings, and through my opinion, I think the origin of Korean War goes back to February, 1945 when the Yalta Conference was held. I will argue and explain in chronological order. The date and the cause-and-effect relationship will be the point in this writing. Also the process of history was too rapid that we may have to memorize many names of associations and people to understand. The Yalta Conference was about how to reform the world after winning Second World War. At the conference, one of the issue was about the Korean Peninsula`s trusteeship. About three months later Adolf Hitler suicides, which caused collapses of the Axis in Europe. So the Allies win the war and they hold the Potsdam Agreement. The Agreement was to discuss how to govern German and to urge Japan to surrender. Also the Allies affirm the Yalta Conference`s treaty. The world was against Japan and Soviet.