Intelligence analysts predicted, in secret papers circulated within the government before the Iraq invasion, that al-Qaida would see U.S. military action as an opportunity to increase its operations and that Iran would try to shape a post-Saddam Iraq.

The top analysts in government also said that establishing a stable democracy in Iraq would be a "long, difficult and probably turbulent process."

"Sadly, the administration's refusal to heed these dire warnings - and worse, to plan for them - has led to tragic consequences for which our nation is paying a terrible price," said Senate Intelligence Chairman Jay Rockefeller, D-W.Va.

Publication of the 229-page document was approved by a vote of 10-5, with two Republicans - Sens. Olympia Snowe of Maine and Chuck Hagel of Nebraska - voting with Democrats to release it.