Jonah, Yalta did not come out of the blue. It had been preceded by Churchill and Stalin’s “half-sheet of paper” discussion in October 1944, when they divvied up the Balkans. The description of the scene in Triumph and Tragedy is vivid, and chilling. There were also the broad vectors generated by our alliance.
The one window of time during which George Kennan was anti-Communist (and for which his latter-day admirers like John Lukacs are retrospectively so) was the period 1944-6, when Kennan was a lonely voice, trying to shove these vectors in a more Soviet-skeptical direction. He did not imagine, however, that they could be utterly changed.
Conservative criticisms of Yalta sound a bit like Andrew Sullivan today. You fools–send in the flying monkeys, and do everything perfectly, like I would!
It’s not so easy in real time.