This is quite an old TED talk, but given what's going on in the Middle East/Africa currently it's well worth a re-visit. Barnett is very dry and very funny - I guess you need a sense of humor to work at the Pentagon.
Barnett's key point is that we have an excellent "Department of War" but we sorely need a "Department of Everything Else". NATO/USA can take down pretty much any military force in the world, however, it's increasingly about what happens next. Libya right now is an excellent example of this. We've taken down Gaddafi's military machine, however, what we do next is unclear from a political, military and reconstruction standpoint.