Today we have hindsight, we know what happened in Germany at the time, and when extermination of people began. Contemporary leaders didn't have that knowledge.

What was known at the time was that jews where persecuted, what was known was that Hitler wanted them gone, one way or the other, as he wanted other groups gone, and it was known what dreams he had of Lebensraum in the East. Present day Poland was already under nazi rule, a future part of the Lebensraum.

Soviet and swedish leaders had basically the same knowledge about Germany, and both countries traded with Germany, as did the US. Trade only stopped when war was declared.

So the Soviet Union can't take any moral credit, they did what they could, they didn't do what they should.