Why did France and the UK declare war on Germany when they invaded Poland, but not on the Soviet Union when they invaded Poland? | AskHistorians Archive Observer

Why did France and the UK declare war on Germany when they invaded Poland, but not on the Soviet Union when they invaded Poland?

by BorisDiawisGod

RiceEatingSavage

u/Georgy_K_Zhukov explains the reasoning behind this here.