For some reason MacArthur didn’t think there were 300,000 Chinese military on the border of North Korea before they invaded.
Comintern.... in this time frame the Soviets and the Red Chinee were buddies. Managed by Stalin. Therefore the compromise of intel on the chinee horde probably was accomplished simply, through the perfumed coterie of army intel pukes who were Macarthur’s “court jesters”. Meanwhile the ground intel advance people knew the chinee were over the yalu, lots of them and coming.
Don’t forget Mac was willing to stop them with nukes since they were after all fodder for the Soviets. But the geniuses with loaded diapers at State were worried this would “bring in” the sovs. The sovs were already “in” there, with 26K troops post WWII, in yet another proxy war of their expansion. So one could say the continuation of the penetration by the Soviets of the FDR admin into the Truman haberdashery closet was quite effective. The red scare and the pussy in the white house. Appeasement has always lead to needless death of warriors. And politicians always lie. Never discount McCarthur’s emperor status at that point. He Was seriously right about Indochina- never get in a land war there (so, of course we did despite Eisenhower warning of the mil/indust complex-—sound familiar?)
Sino-Soviet split happened later with a sino-soviet border war that has been largely overlooked.
Parenthetically WEB Griffin has his character McCoy in the thick of this with some interesting plausibilities of the time and the nascent OSS/CIA vs. Army intel.
But, uh it’s OK we have John Kerry on the case... a comintern operative puke gigolo. A cast of characters and we are in bad hands.... again.