This is possibly the most difficult part of history to look at because political agendas get in the way of historical facts. Through massive propaganda, people believe that it was only Jews that were resettled elsewhere
take a look at the Soviet Union and their ethnic cleaning of Germans from the Baltic area at the end of the war. Also, take a look at the very beginning of the war when the Allies declared war on Germany on 1 September 1939 for invading a part of Poland that was originally Germanys during the German Empire created by Otto Von Bismarck on January 18, 1871...the rest of Poland was made into a protectorate. The Soviet Union invaded Poland as well, but yet the allies turned a blind eye to that. The Soviet Union invaded Finland, once again the allies turned a blind eye to that as well.
Also, the Federal government did everything it could to provoke a war with Germany, if you are thinking the they stayed out of the war because they were to soft on Hitler you are dead wrong. They just didnt have the excuse or enough support from the American people and soldiers to go out and die. You refer to minority groups suffering under the Third Reich as an reason for war, well, it is hard to rally an entire nation to a war they dont understand. So until the Federal government had enough of a reason to go to a war, they had to just provoke one with the Third Reich until finally Hitler declared war against the United States and ended all diplomatic relationship. That was when the United States unleashed all of its military power possible.