After toppling Saddam Hussain, the Americans should have made Iraq a federal republic, with more power to the provinces. That is the only way to unite a country which is deeply divided along the ethnic and sectarian lines. But what they did was to create another dictator in the form of Nouri Al Maliki. IMO, Iraq should be divided in to 3 federal subjects (one each for the Sunnis, Shiites and Kurds), with the minorities such as Yazidis, Assyrians and Shabaks having their own autonomous regions.
At what point should the people of Iraq taken the lead in creating the solution you believe to be most beneficial to them? The American's liberated the country from a Dictator and the remaining leaders did not have the courage to lead - or at least that's how it appears.
The Americans are damned if they do and damned if they don't...