It went so well in Japan and Germany, too! What did we do wrong? Not kill enough of the Iraqi military when we were fighting them? Not employ enough of them during the occupation?
We supported the elected Shite government but that left the Sunnis out in the cold, to form IS. Should we have partitioned Iraq into Sunni, Shite, and Kurdish nations and then occupied the three areas independently? Each could have formed their own alliances with Saudi Arabia, Iran, and nobody respectively. No IS, but three more little gulf states with a lot of oil.
