The US Senate Committee on Intelligence has just released an interesting report on
Prewar Intelligence Assessments About Post-war Iraq (10MB .pdf). It mainly consists of two declassified documents circulated to about 800 US officials just before the war was launched (January 2003) and marked "SECRET" at the time (thus ensuring they provided much of the content for "backgrounders" to the press). Fascinating reading. Even though the deletions and large circulation exclude any real insight into policy maker thinking it certainly confirms that the entire US Government (including Congressional committees who were also on the circulation list) were fully aware of estimates that the Iraq war would be long and difficult and had very little to do with WMDs.