Maki's directly mentioned aliens and the war several times, along with implications of them being reasonably equivalent enough for the war to actually be a war rather than a "they're basically gods" thing.Honestly, I'm beginning to think that the "space war" is more about Room than actually Outer Space. It's possible that people may have just thought it involved aliens from outer space and went with it.
Noriko also seemed to imply it's actually about the economy:You don't have permission to view the spoiler content. Log in or register now.
I wouldn't be all that surprised to find out that the gods and beings that Sensei has been seeing are "aliens" though. Talking plants, angels, talking birds, etc, probably even the entire cast could be aliens all playing a game.
Could be that by the war being economic, it could be something like fighting over mining rights to some very rich but barren planet. But that's neither here nor there. I was just lamenting that he'd use that as a plot point to explain the near total lack of men, then deny us the chance to probe alien mystery orifices.