That's exactly what we said before the Maginot Lines of France and before the rise of the Nazi party. Let the Eurpeans die. We thought we were immune until Pearl Harbor.
Isolationism didn't work for us then, and it will not work for us now.
I've never figured why anyone thought of the US as isolationist. Any more than Brazil or Argentina was isolationist, that is. The real problem is that the countries directly at risk are not merely isolationists - they are fantasists. Unless countries that act this way pay the price, everyone else will fall back on Uncle Sam as the unpaid janissary of first resort. We've defended them repeatedly in the past. It's time the training wheels came off.
Bottom line is that I’m not thrilled with the idea of Uncle Sam as a military slave to the world.