Hitler’s strategic program for Greater Germany was based on the belief in the power of Lebensraum, especially when pursued by a racially superior society.[9] People deemed to be part of non-Aryan races, within the territory of Lebensraum expansion, were subjected to expulsion or destruction.[9] The eugenics of Lebensraum assumed it to be the right of the German Aryan master race (Herrenvolk) to remove the indigenous people in the name of their own living space. They took inspiration for this concept from outside Germany.[9] Hitler and Nazi officials took a particular interest in manifest destiny, and attempted to replicate it in occupied Europe.[11] Nazi Germany also supported other Axis Powers’ expansionist ideologies such as Fascist Italy’s spazio vitale and Imperial Japan’s hakkō ichiu.[12]
That’s my understanding as well, with some “Roman” origin claimed, possibly as propaganda given how the Nazi party liked connecting themselves to ancient Rome as some kind of claim to legitimacy.
I’d love to be able to add the Bellamy salute inspiration bit in when I do have this conversation with folks, but I’d need a better source before I do.