The U.S. fleet did have a warning at Pearl, but didn't really respond to it. (Oh yes, the had a radar from the Brits if I recall right, and the Japanese aircraft were plotted inbound)
McArthur also had a reasonable warning in the Philippenes, since the air attack came well after Pearl and he already knew. Yet again, he was well to sleepy.
Poland got rolled up fairly easily. AFAIK France falling in about the same time was much more costly for the Germans. And remember, the push came through the lowlands, not straight into France (It was too well defended), and I am not sure the Germans had that much armour available in 1939.
Anyway, a good point about Stalin and Poland. The USSR actually went for the Polish when the Germans were only 2 weeks into the invasion, and had a fairly easy superiority. After all, it was not winter as they laterhad in Finland. So, IMHO, had Hitler rolled west on september the 1st, it would only have been a week or so before Stalin had rolled into Poland.
He actually let Hitler do a good bit of the job, I guess he could have moved earlier. What a Ba$-tard
