MacAuthor could not believe that he had been order to defend South Korea, he was dumb founded by the change in policy. There were zero plans for the defense of South Korea. Now tasked with defending the south he did what any good commander would, he threatened the flank of the enemy by visiting the nationalist Chinese on Taiwan and made it known that on Taiwan there was an army ready willing and capable of invading mainland China. This threat was taken seriously by the Chicoms, tying up many of their troops for the purpose of defending against a possible invasion. Until that is, the genius Truman ordered the 7th fleet to patrol the Taiwan straights to ensure Shan Ki Sheck (sp?) did not invade China. Guess where all those troops that had been tied down went once Truman secured the enemies flank for them? Truman was an idiot.
Unfortunately, MacArthur was an egomaniac who was really vague on how the US Constitution works. It is not an Army general’s job to make strategic foreign policy decisions that might get the US into war with another country. Whether the decisions he made might have been more appropriate is quite beside the point.
MacArthur lucked out at Inchon and then failed miserably in the North.