Having been born in a socialist democratic Britain in 1951, to a family who had several members active in World War II, it is unlikely I would have much first-hand knowledge of pre-war US policy. But I did at least get an education that allowed me to read about it. Despite protestations from the present president, the US has always put America first and any benefit gained from its actions were in their best interests, especially with concern to oil production vital to its industrial and military concerns.
America’s late involvement in World War II was spurred by the realisation that the combined industrial might of Japan and Germany would completely realign the world order, and it was essential to not let that happen. That Scandinavia was “saved from the Nazis” was not of a primary concern for either the US or Britain, but it is interesting to note that one of the American allies in that war, Russia, was of far greater threat to the Scandinavians, and still remains so. It is obvious that America was not assisting its military allies – Russian, Chinese nor European – to avoid Nazism, just has it hasn’t been assisting the ordinary citizens of the many other countries it has been involved in to avoid any form of peasant revolt.
As a final point to demonstrate how right they were in recognising their industrial enemy, it’s interesting to see how despite wartime defeat, the Germans and the Japanese have emerged as the victors in the industrial battle and the Americans much prefer to drive autos made in those countries than they do home-produced ones.