In September 1995, NATO finally bombed the war to an end and within a couple of tough months Richard Holbrookeforged a peace agreement. It turned out that the United States, along with NATO, could make a difference — and with relatively little effort. No boots went on the ground. The operation was conducted from the sky.

We cannot be the world’s policeman, I know. Still, the world needs a policeman and who can it be if not the United States? We have to pick our moments, but where we can intervene, as we did successfully in Libya, we must — not alone, surely not alone, but in concert with others. Where you can do something, you must do something.

Some bad days are coming. Maybe history doesn’t repeat itself, but human nature does. Contracting economies mean expanding hatreds. This is no time to mindlessly cut the Pentagon budget. This is no time to turn inward.