Why is it America's Job to Defeat ISIS?

"And if the Turks and Sunni Arabs are unwilling to put boots on the ground in Syria, why should we? Why should America, half a world away, have to provide those troops rather than nations that are more immediately threatened and have armies near at hand?" Good question. I don't agree with paleo-conservatives that much, but when I do, it's usually about the folly of foreign military interventions.