The basic idea behind this article is that the UN and the US conduct nation building in very different ways. The US way was to go in to a country with overwhelming military force. The UN way was to go in with fewer forces and try to be more friendly.
Recently, it argues, the US has started to try to be more like the UN -- to do nation building the UN way. This is not a good idea, and the US should go back to its own way.
At the same time, the UN has done a better job of learning from its mistakesn that the US has. So the US should emulate the UN in that way.