Actually, MacArthur's plan was far less extreme. He proposed only nuking the area along the Yalu River and North Korean border so the Red Chinese couldn't reinforce or supply the North Koreans.
We alone had nuclear weapons at the time. MacArthur was a thoroughly decent human being who believed in minimum casualties. He was proud of retaking the Pacific with fewer casualties that Mark Clark lost taking Anzio Beach.
MacArthur's speech "Duty, Honor, Country" ought to be required reading for every school child in America.
Not that I’m disagreeing with the sentiment that MacArthur should’ve gotten his way, but during the Korean War, the Russians also had the bomb and surely would’ve come to the aid of the Chinese and Norks.
The previous poster spoke of 1946, when we still had an atomic monopoly. The Kuomintang hadn’t been driven off the Chinese mainland yet, though, and the Korean War had not yet started.