Prior to the war in Iraq many U.S. academics--myself included--were skeptical of the war plans. In my own case, I wrote that we knew little about Iraq and its political dynamics and that the country was a poor candidate for early democratic transformation. I was particularly convinced that the Shi'i community had emerged from the 1991 intifadah far closer to Iran than war proponents suggested. I also argued just after the war began that the U.S. had a few months to "internationalize" the occupation, and after that the U.S. would find itself in a self-checkmate position, wherein it would neither be easy to stay without great challenges or leave without great dangers.
In off-the-record conversations over the past few years, I also learned that government analysts were also reaching similar skeptical conclusions prior to the war. Here two NIC (National Intelligence Council Assessments are released from prior to the invasion, revealing some of the skepticism: about the likely reaction of the Iraqis to the invasion and likely impact on jihadist currents.
Assessments Made in 2003 Foretold Situation in Iraq - washingtonpost.com