Undersecretary of State Decides to Step Down - washingtonpost.com: "William Burns, his successor, is a former assistant secretary of state for the Near East and ambassador to Jordan. In 2002, he co-authored an internal memo with Ryan C. Crocker, the current U.S. ambassador to Iraq, titled 'The Perfect Storm.' It bluntly predicted that toppling Saddam Hussein could unleash sectarian and ethnic tensions, that the Sunni minority would not easily relinquish power, and that neighbors such as Iran, Syria and Saudi Arabia would try to influence events."
This has been reported before, perhaps in George Packer's book. I can't recall right now.