The wise prince would use both methods, where each is appropriate, and would exercise the restraint and judgement to know when and if to do so.

Certainly true, but this is similar to saying "a wise investor will only put his money in stocks that are going to increase."

We already know that isolationism isn't possible in our modern era. We were occupying no countries at all when our enemies attacked us.

We also have a pretty good idea that invading and occupying every country that means us ill isn't going to be a workable solution, either. We're pretty much maxed out at two, and there's a lot more out there.

It would be great not to be the world's policeman, but at this point, looking around at the U.N. and other alternatives and how they're working out in Africa and elsewhere, we seem to be left with a choice between America doing it or nobody doing it. Even NATO in Afghanistan has the U.S. carrying most of the weight, although a few other NATO countries have done pretty well in supporting the effort.