Perhaps we could use a New Rule: When you take over a place by force, expect to pay the (karmic and/or other) price.
Well, Americans certainly paid the price for their system of slavery in the apocalypse of the Civil War and the subsequent soul-destroying racism and crippling of the South.
They will also pay the karmic price for the past fifty-odd years of war crimes and evil exploitations around the world. In fact, the karmic pay-back has already begun.
Curiously, the British haven't (as yet) suffered nearly as much karmic pay-back for their crimes as you might expect. Perhaps it is because they had enough sense to throw in their hand and get out of the Empire Biz when it was clear that the show was over.
Americans will never have as much good sense as the British, though. So expect a rough ride downhill.