During World War 2 it was believed that the Germans will never change and will always be a source of conflict in europe (or worse). There were wild ideas like the Morgenthau Plan to completely dismantle any German ability to wage war.

But it turns out a very militarized nation can become completely pacifist after suffering a complete utter defeat, suffering and destruction.

Culture can change, just like 1990s Russia was a break from past and future Russia. However the 1990s were a disaster and thus the culture changes went to the opposite side