Well hitler was fascist so I’m guessing he would have supported it
It's mainly because of A and B, because after the war, the industrial resolution happened, and farmers are replaced by machines, farmers has no work to do, their speed is no compare to the machines, so they must move to another place. Also the population in Europe is growing in a extremely fast speed. Hope that helps :)
It was the idea of "Manifest Destiny" that was the belief that it was God’s plan for the United States to own most or all of North America, since people thought the US was "destined" to occupy all the territory from the Atlantic to the Pacific.