Our Invasion of Iraq eliminated the force structure Saddam imposed to keep the diverse factions in Iraq from battling each other. That force structure, although brutal, kept the sectarian factions from doing what we see every day in Iraq. From the beginning, Iraq was an artificial country composed of factions that hated each other and were kept in line by FORCE.
We have exchanged the force Saddam imposed for a vacuum that has allowed these factions to emerge and assert their individual power structures. The loyalty of the Iraqi people has NEVER been to the country but to the faction that each person belonged to in Iraq. Colin Powell was prophetic when he said, break it and it is yours. Bush has done just that and is unable to make it hole again. His idea of a Democracy will not work because there is no desire for real unity among the people of Iraq. Their loyalty is to being a Kurd, Sunni and Shiite NOT an Iraqi.
History will not look favorably on what we have done in Iraq and the real problem is how to limit the consequences of our invasion from spilling into the other countries in the region.