It's a theory that's been suggested by a few, and I like the idea.

What if, after the invasion, an outpost was built somewhere in Outworld, to better surveil "the enemy", and also for the sake of more nefarious purposes (like Outworld possessing wanted resources)? What if the installation of that outpost brings the military in conflict with Outworld natives (like Li Mei)?

I wouldn't mind this stage being located on Earth, but it being located in Outworld offers some interesting possibilities.