>> This leads to hugely destructive wars.

> Nonsense. Self-interest != hostility.

Right. Just because someone is looking out for their own self interest doesn't mean that they are constantly "winning" a zero-sum game with someone else. In fact, sometimes cooperating is the most self-interested move you can make...

Which is exactly why all of these other nations might be "upset about the US change in behavior" without necessarily prescribing any course of action that isn't also in the US's best interest.