Most often we hear about a karmic debt to pay, a kind of payback for some unrighteous deed in the past--something we've got coming to us. Different in form and not necessarily proportional, it might come from out of the blue. But . . . (this is something to think on too) there's good karma too.
A nation, as an individual, can build up a storehouse of karma. "Stirring Li Chao" and it's companion book of proverbs attempts to confront the issues that foul America and darken its days in the sun.