Sometimes a war is justified, and coming to the aid of an ally getting invaded is a damn good justification.
Especially if that ally is simply asking for more hardware and not asking for feet on the ground.
Edit: Fixed the link, it was broken for some reason though it worked earlier today. IDK this mirror should work though
Poland went to war with basically all their neighbors at this point and were largely supplied by Germany. There are anxieties about this history to this day in Western Ukraine, Belarus, Slovakia, and Czechia, because the Poles massacred a lot of people. Its one thing to want independence, its another to massacre innocent civilians for fun.
It wasn't 'appeasement', it was active collusion.
The Soviet Union had just got out of a Civil War and had almost no industry. They had roughly 10 years to build an industrial base capable of defeating what essentially amounted to all of mainland Europe. They were a feudal society before WW2 and were starting from scratch. And they won, so clearly what they did, communism, worked.