Actually, it's the other way around: Hitler never posed a threat to the United States, and in fighting him, we got the rise of the USSR and communism around the world to contend with for half a century. Remind me how that was good, again?
Hitler should have been swallowed. Once he completed the take over of Europe, Germany would have been the super power in the world. Why would we want an oppressive, fascist, socialistic society as a super power? lol Also, why should we sit back and let him incinerate millions of Jews? IMO it is more wrong (morally) to allow that to happen.