See, that's the problem. You're still seeing it like a military victory problem. An effective police force means that crime is minimized, and that criminals are captured quickly and dealt with. It does not mean crimes never take place.

A mortar round is fired, troops are deployed, and the mortar firing criminals are eliminated. It never ends, but the criminals are dealt with as they arise. What else can you do?

I don't like it, but I don't see any other direction that this is going in. Libertarians say we might have been a lot better off with a more isolationist foreign policy during the twentieth century, but a good case can also be made that if we had we would currently be a North American island surrounded by totalitarian Nazi and Soviet monsters. There are no easy answers.