WI: MacArthur gets his way; US bombs China in Korean War

After China intervened in the Korean war and pushed the UN forces back out of North Korea MacArthur publicly advocated extending the conflict to the Chinese mainland through bombing, perhaps even through the use of atomic weapons. An exasperated President Truman, who was determined to keep the "Police Action" (as the Korean War was referred to) limited to the Korean Peninsula and famously fired MacArthur over the issue. In the end the see-saw war became a military stalemate and the Peninsula remained divided to this day, while China and the USA later had a rapprochement. But what if MacArthur had gotten his way (Either with or without Truman's ascent) and the US responded to the Chinese invasion by launching a bombing campaign (nuclear or conventional) on Chinese cities? How would this have affected the outcome of the Korean war, or the future development of China and the Cold War as a whole? Perhaps most importantly how would the USSR have responded to such an attack on their biggest Communist ally? Would we see direct, open conflict between the US and USSR, perhaps leading to a nuclear exchange?

BTW, here is a link to a great documentary on the Korean War from the excellent "Cold War" series in case anyone is interested:
 
Best case scenario, the US loses its moral standing abroad for a generation. Truman would have never approved it so MacArthur is court martialed and possibly charged with war crimes. Worst case scenario, Stalin feels compelled to support his communist brethren and attacks Western Europe.
 
Best case scenario, the US loses its moral standing abroad for a generation. Truman would have never approved it so MacArthur is court martialed and possibly charged with war crimes. Worst case scenario, Stalin feels compelled to support his communist brethren and attacks Western Europe.

Stalin knew better. He knew Russia would be flated by the US with their Atomic bombs. And besides, he doesn't have much time left.
 
How was the US prepared to react at this time to a Soviet invasion of Western Europe? The UK and France don't have atomic weapons of their own at this time so I guess they would have to rely on the US arsenal to deter the Soviets from pushing towards Paris after central Europe was overwhelmed.
 
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