France & Britain tried; we watched. Does nobody else find irony in our propping up the USSR, Hitler’s partner in dividing Poland? They killed people, too; just different groups than the Nazis did.
And Stalin hated the Jews as much as Hitler did, I'm sure he didn't mind the favor Hitler did for him in taking care of the Russian's "Jewish Problem", before defeating him.
You might find it hard to believe, but there was a time when every war on the face of the earth was not considered to automatically involve us.
And while you have a case of the fainting vapors over Poland, you say nothing of Ethiopia. You think we should have intervened in Ethiopia when Italy invaded?
For perspective, Poland as a nation had existed about 20 years in 1939. From 1815 until Versailles in 1918, most of it fell it fell under the Russian Czars and under Prussian rule starting with Fredrick II.
In WWI 21 years before, 38 million people had died. America saw Germany and Russia invading Poland and disliked it, but basically saw it as restoring the pre WWI territory they had claimed for 200 years.
While Britain and France, had alliances, there was no way America was up for going to war over Poland. No more than we would have over Ethiopia.
And remember, you are looking at hindsight. Katyn was carefully hidden for a few more years. The holocaust was in its infancy and was also hidden.
Its bullcrap for you to say America did nothing.
Didn't try very hard, they did little to nothing to aid Poland, the cause of their declarations of war. And although costly to both nations, the offensive of 1940 was a German offensive, the French and Brits would have been happy to continue the phony war. With greater foresight the US should have foreseen future involvement, and attempted to exert her influence. Just as France and Britain should have stopped Hitler in the Rhineland, which was well within their capabilities. My understanding is that German commanders had orders to withdraw if confronted by any serious French resistance.