The USA only agreed to join the war after Pearl Harbour in 1941 when the actual war started in 1939. We got Lend-Lease but the USA demanded it all back at once after the war, leaving the UK in financial difficulties. What have we got to be grateful for USA? We saved your bacon as well.
Even then, I seriously wonder if they'd have got involved in Europe if Hitler hadn't made their minds up by declaring war on the USA.
From what I read a long time ago, there were many Fascists in the USA then already and many industrialists secretly funding Hitler. They flourished after the war too, unfortunately. Hitler was like Trump in a way. He was stupid.
Personally I think Trump mirrors Mussolini more than Hitler. Lazy complacent people who don't bother to vote. They don't really like any of the alternatives and they think this feller will shake thing up a bit. Next thing is they're surprised when things go pear-shaped.
He'll be lucky if he doesn't end up like Mussolini or Ceaucescu but more likely he'll die in office and be given a pompous funeral by the GOP.😠