U.S. intelligence analysts predicted, in two papers widely circulated before the 2003 Iraq invasion, that Al Qaeda would see U.S. military action as an opportunity to increase its operations and that Iran would try to shape the post-Saddam era.

The top analysts in government also said that establishing a stable democracy in Iraq would be a long, turbulent challenge.

Democrats said the documents, part of a Senate Intelligence Committee investigation released Friday, make clear that the Bush administration was warned about the challenges it now faces as it tries to stabilize Iraq.

"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.

But some Republicans rejected the committee's work as flawed. The committee's top Republican, Sen. Kit Bond of Missouri, said the report's conclusions selectively highlight the intelligence agencies' findings that seem to be important now, distorting the picture of what was presented to policymakers.

He said the committee's work on the Iraq intelligence "has become too embroiled in politics and partisanship to produce an accurate and meaningful report."

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 — joining with Democrats in the prevailing position.

Asked about the report at his Thursday news conference, President Bush stood by his decision to topple the Iraqi regime. He said he firmly believes the world is better off without Saddam Hussein in power.

"Going into Iraq, we were warned about a lot of things, some of which happened, some of which didn't happen," he said. "Obviously, as I made a decision ... I weighed the risks and rewards of any decision."

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 once-classified 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 identified in the Senate report.

Among other conclusions, the analysts found:

— Establishing a stable democracy in Iraq would be a long, steep and probably turbulent challenge. They said that contributions could be made from 4 million Iraqi exiles and Iraq's impoverished, underemployed middle class. But they noted that opposition parties would need sustained economic, political and military support.

— Al Qaeda would see the invasion as a chance to accelerate its attacks, and the lines between Al Qaeda and other terrorist groups "could become blurred." In a weak spot in the analysis, one paper said that the risk of terror attacks would spike after the invasion and slow over the next three to five years. However, the State Department recently found that attacks last year alone rose sharply.

— Domestic groups in Iraq's deeply divided society would become violent, unless stopped by the occupying force. "Score settling would occur throughout Iraq between those associated with Saddam's regime and those who have suffered most under it."

— Iraq's neighbors would jockey for influence and Iranian leaders would try to shape the post-Saddam era to demonstrate Tehran's importance in the region. The more Tehran didn't feel threatened by U.S. actions, the analysts said, "the better the chance that they could cooperate in the postwar period."

— Military action to eliminate Iraq's weapons of mass destruction would not cause other governments in the region to give up such programs.

As numerous investigations have found, the intelligence agencies of the United States and its allies were wrong about Iraq's supposed weapons programs.

Because Intelligence Committee members couldn't agree on clear conclusions about the intelligence, they saved their analyses for appendices attached to the report.

"The most chilling and prescient warning from the intelligence community prior to the war was that the American invasion would bring about instability in Iraq that would be exploited by Iran and Al Qaeda," wrote four Democratic senators — Rockefeller, Ron Wyden of Oregon, Evan Bayh of Indiana and Sheldon Whitehouse of Rhode Island.

Meanwhile, four Republican senators — Bond, John Warner of Virginia, Orrin Hatch of Utah and Richard Burr of North Carolina — wrote that the report exaggerates the importance of the pre-invasion assessments. They said the reports weren't based on intelligence information, but instead were speculation from experts in and out of government.

"They were no more authoritative than the many other educated opinions that were available in the same timeframe," the Republicans wrote.