At present, many people think that it was put forward by douglas macarthur, the then commander-in-chief of the United States in Japan, but later the military declassification was wrong. Douglas macarthur just wants to destroy Korea, occupy the Korean peninsula, win more victories, and then return to the United States to run for president with great military achievements. From a purely national strategic point of view, the United States is right, following the example of Japanese invasion of China, first occupying Korea, then using Korea as a forward base, and then attacking China. However, after World War II, the United States invested heavily in the civil war in China, but its power in China was completely defeated. American high-level officials have realized that the Kuomintang is corrupt and incompetent, and the so-called mainland counterattack by the Kuomintang is impossible. So it is inconceivable to directly attack China and provoke the Soviet Union. At that time, President Truman's idea was to maintain the 38th parallel, and Truman and MacArthur were politically hostile. MacArthur and Eisenhower, an old subordinate who later ran for president, were also politically hostile. The top leaders of the United States joined forces to suppress the Japanese local tyrant MacArthur, so this statement was deliberately put forward by Chairman Mao in order to intervene in the situation in North Korea. In fact, Chairman Mao's worry is correct. In case the Korean Peninsula is infiltrated by the US military, China will directly confront the US military in the Yalu River. At that time, there happened to be the support of the Soviet Union. It is of greater political significance for China and the United States to wrestle and fight in North Korea.