Yes, that was definitely over the line for the Soviet Union to demand that Finland hand over a buffer zone. But in fairness the soviets did have some reason for

Yes, that was definitely over the line for the Soviet Union to demand that Finland hand over a buffer zone. But in fairness the soviets did have some reason for concern. Finland had historic ties with Germany. Germany had helped the non-communist side of the Finnish War, notably by training the Jaeger troops. Still, I expect Finland would have been only too happy to sit out the war as a neutral, like Sweden did. But the Soviets didn't give them that option.