“Truman should have allowed MacArthur to roll all the way to the Chinese border.”
Dude, we did roll all the way to the Chinese border.
The Chinese came in with their tennis shoes and one weapon for every few men, and pushed us all the way back to the 38th parallel.
The Chinese have millennia of experience with getting unwilling men to fight. They lost 40 million just in the Tai Ping rebellion alone.
If they thought they could come out of a nuclear exchange with a piddling little 40 million dead, they wouldn’t be deterred by fear of the casualties.
They did. Then their populace discovered the bourgeois life was not so bad. Now the same 40 million would drown the PLA in their own blood. Xi's concern is not sabre-rattling, it is continental civil war after a regional gunfight gets out of hand.