The conclusion to draw from that is not that all conflict and cruelty outside the New World is irrelevant to Americans and their interests. You’re a bit older than me, but neither of us have experienced a world with a truly aggressive near-peer power. We’ve lived our entire lives on the laurels of our grandfathers’ victories in Europe and Asia. The resulting international system organized around fixed borders, the rule of law, and low barriers has allowed to flourish the multitude of mutually beneficial trade relationships that support literally the entirety of the only way of life either of has ever known.
It’s an unstable equilibrium. To not defend order against might risks knocking the whole thing down - and then who knows? Maybe we carry on with China and the rest of APAC while Russia dominates Europe? Maybe we live a decade or a generation of poorer, meaner, more isolated lives confined to the New World? Maybe the expansionary impulse brings them, eventually, to our shores?