Initially America had entered the Korean War with the aim of evicting the NKPA from South Korea and restoring the status quo ante bellum. By the time of Inch'ŏn President Truman had made the decision to enlarge the war. American forces would cross the 38th Parallel, wipe out whatever was left of the NKPA, depose the Communist regime of Kim Il Sung, and unify Korea under a single, popularly elected government.
The decision to invade North Korea was unanimously supported by the senior members of the Truman administration: Dean Acheson; George Marshall, the new secretary of defense; Omar Bradley and the other members of the JCS; and, of course, MacArthur, his GHQ, and his senior field commanders, Johnnie Walker and Ned Almond. The decision was also approved by Dwight Eisenhower, still president of Columbia University.
Many factors influenced Truman's final decision:
• An overpowering urge to get rid of the "Korean problem" once and for all. If the Communist government of North Korea remained in power, there was every likelihood that it would rebuild the NKPA and attempt to invade South Korea again. Such an invasion could be deterred only by maintaining American troops in South Korea indefinitely - a costly, unpopular diversion of American military resources to a non-strategic area. Moreover, Washington had to confront this reality: Syngman Rhee had not the slightest intention of stopping his ROK Army at the 38th Parallel. He was hell-bent to unify Korea by force. The ROK Army could be restrained only by American military force, an unthinkable course of action.