diplomat1824, I think it's pretty clear that the main reason for this latest nuttiness in North Korea was to make the world respect the announcement of his successor, who's only about 25.
http://news.bbc.co.uk/2/hi/asia-pacific/8078324.stm
You're pretty naive to think everything would be so easy in defeating China. For one thing, it's no where near a guarantee that China would support North Korea again. How could any nation truly support such a regime. At any rate, in the event of a war with China, we probably could win conventionally in the air and at sea. In fact, almost certainly. I highly doubt an actual invasion where US soldiers march through Beijing is possible, though.
Even if the US totally won, we'd lose because a conflict, even a very limited one or a serious standoff, would completely wreck the entire world economy. Short of a direct, unprovoked Chinese invasion of Taiwan or a naval clash over the South China Sea, there will never be a shooting war between America and China.
Stripy, you overestimate China in the early 50s. The US fought a limited police action in Korea, so we had one hand tied behind our back once China got involved. Truman rightly knew that a war in China would be a terrible distraction to the bigger threat of the Soviet Union in Europe. We didn't draw so much as we decided to stop fighting seeing a other places had a higher priority.