To add to other links:
https://en.wikipedia.org/wiki/Phoney_War
Also Russia actually invaded Poland together with Germany:
https://en.wikipedia.org/wiki/Molotov–Ribbentrop_Pact
It was only after Hitler attacked Russia they switched sides and became allies to the West, but West let them keep the land they took.
To Poland events of world war 2 continued until 1989 when it finally escaped Russia’s control.
I’m unfamiliar with this topic, which politicians/countries changed their laws?