If what has been going on in the world outside the purview of "Fortress America" is supposed to be "peace", then it could stand a whole lot of disruption.
Peace is a consequence of conclusive victory and the resulting amity of reconciliation, not the absence of war acts. Peace may forever elude the human race, but the ideal of peace is not served by abject surrender to bullying tactics.
Obviously the author of this piece doesn't understand that insinuating ourselves into every ancient ethnic and religious war, most of which we don't begin to understand, can only result in our being seen as a participant in such conflicts. Once we involve ourselves, the extension of these disputes to US soil and interests follows as night follows day.
Playing policeman to the world is expensive, doing so without a clear picture of what your objectives are and the obstacles to achieving them is idiotic. On both counts, I think we're better off not wandering around the globe looking for dragons to slay. There are plenty of them out there, just as there have always been and as there always will be.
What fortress America? You mean the one being invaded legally and illegally by millions of people a year?