[r9etb]

I think the point is that the Poles and Soviets had fought a war in the recent past, and the Russians lost. The Soviet invasion of Poland has to be understood in that context.

Also, it is important to acknowledge that the Poles fought several wars in the '20s and '30s, including in Upper Silesia, which had a significant German population to whom Poland was not charitable.

Poland's activities of the previous decades had thus made it an attractive target for both Russia and Germany. Not that the invasion was at all justified -- it just made Poland an obvious first choice for the expansionist aims of both invaders.

[Lukasz]

You know that if you really want to attack someone you will always find a reason to do it. For example first polish-german war was in 972 and what is the reason why they came back so many times? You always find a reason.