What if a country is brutally oppressing and slaughtering its own citizens? Or beating up and plundering its neighbors? Or both?
Do you sit there with your hands folded and piously say, "It's not any of my business?"
I think Pastor Niemöller's famous quote applies here as well. If you're not familiar with it, Google it.
When the Nazis started sending their own people to death camps, and then invaded Poland, if a coalition of countries—such as the U.N. or NATO (which did not exist then, but an ad hoc coalition should have worked as well) had gone in and removed Hitler and the Nazi regime right then, history would have been a lot different and millions of lives would have been saved.
Of course, if you're worried about the earth's increasing population density, allowing the tyrants and dictators to purge the "undesirables" from their societies is one way of helping to alleviate that. . . .