Human nature may be the same, but it differs based on context. Humans act differently in a threatening high risk, low order world than they do in a more stable, lawful world. There is normalization, because in a pre-nuclear, pre-military alliance, pre-diplomacy, pre-world-police world you had to be much more ruthless and cunning as a state. The norms for people were completely different.
I see no evidence that they do act substantially differently post nukes given everything going on in the world in the news today. Regardless, this thread is going off topic, have a good day.