“I must have missed all of those Soviet troops pouring across the Yalu River.”
Yes, carrying American weapons supplied by the Soviets via lend-lease from WII. The Chinese clearly supplied bodies, but the Soviets supplied the money. Always follow the money. After Stalin died the power struggle in the Soviet Union was around how much of their economic output should be expended on “guns” rather than “butter”. The “butter” boys won and a cessation of hostilities was reached in North Korea soon thereafter, because the Chinese had no industrial infrastructure to support the war.
I see your point better now. Stalin and Mao were close during those years. It was Stalin who propped up Kim Il Sung before Mao took power in China. But after the war, they were clearly in the Chinese camp.