Quoting from Robert Jervis’ The Meaning of the Nuclear Revolution: Statecraft and the Prospect of Armageddon, a possibly apocryphal yet compelling anecdote from the memory of Ambassador Averell Harriman:

As Harriman later remembered it, the Soviet leader [Khrushchev] declared that America could not maintain its position in Berlin by force: after he signed a peace treaty with East Germany, any attempt to reassert Western access rights would mean that “rockets would fly and the tanks would burn.”…”I laughed. He asked, ‘What are you laughing about?’ I said, ‘What you’re talking about would lead to war and I know you’re too sensible a man to want to have war.’ He stopped a minute and looked at me and said, ‘You’re right.’ “