The Japanese surrendered to the Soviets above the 38th parallel and to the US south of the 38th parallel in 1945(end of WWII). Both sides agree to reunite Korea with unifying elections in 1947 (which never happens). On June 25th 1950, the north Korean communist forces crossed the 38th parallel into south Korea being supported by the USSR. On June 27th, the U.N. resolution allows forces to defend south Korea (most troops were from the US). By september of the same year, the United Nations had pushed back the North Koreans across the 38th parallel. After a debate about freeing all of Korea from communism, on October 7th, a new resolution allowed for troops to enter north Korea. The war now becomes offensive. The united nations pushed the north koreans all the way up to the Yalu river. In november, 300,000 Chinese “volunteers” supporting the USSR’s goals entered the war. The Chinese would push the UN’s forces back across the 38th parallel. Nuclear power was debated by the United States, but eventually would be stopped by Truman in a fear of starting WWIII. The aftermath would show it as a police action (as there was no formal declaration of war) necessary to keeping democracy abroad, Korea remains divided at the 38th parallel and 54,200 Americans died(34,000 is more accurate).