This summer has seen new conflicts with deadly consequences everywhere from Africa to the Middle East to Asia.

The scope of these challenges has led Stephen Walt, Professor of International Relations at Harvard's Kennedy School of Government, to write that it's time for the U.S. to "walk away and not look back."

"Most of our interventions have actually gone the opposite of what we really wanted," Walt says.  He's not proposing a new era of American isolationism. but says the U.S. should "stop trying to manage the politics of the region."