It's amazing what we're finding out now.

The investigation reviewed assessments from a number of agencies but focused on two January 2003 papers from the National Intelligence Council: "Regional Consequences of Regime Change in Iraq" and "Principal Challenges in Post-Saddam Iraq."

Those papers drew from expertise within a number spy agencies and were distributed to scores of White House, national security, diplomatic and congressional officials - most of whom were listed in 81 pages of the Senate report.

The full report (PDF).

I think they could have been told that invading Iraq would bring down the whole universe and they still would have gone in. The problems in Iraq were and are inconsequential to them.