The key assertions of the Bush administration used to justify the invasion of Iraq - that Saddam Hussein had chemical and biological weapons and was trying to start up a nuclear weapons programme - were wrong, a US Senate Intelligence Committee report concluded yesterday.
The report is a major international embarrassment for the Bush administration which is now judged by the Republican-led committee to have used wrong information to convince its allies on the need to invade Iraq.
The information that sent the nation to war was flawed, the Republican chairman of the committee, Senator Pat Roberts, said when launching the 400-page report which found there was no intelligence to back up the administration's claims about Iraq's unconventional weapons.
"The assessments that Iraq had chemical and biological weapons and could make a nuclear weapon by the end of the decade were wrong," he said.
"They were also unreasonable and largely unsupported by the available intelligence. This was a global intelligence failure." The Democratic deputy chairman Senator Jay Rockefeller went further.
"We in Congress would not have authorised that war with 75 votes if we knew what we know now," he declared.
An intelligence assessment in October 2002 that Saddam Hussein had WMD was used to persuade the US Congress, including a majority of Democrats, to give the president authority to go to war.
The committee did not investigate how the weapons claims might have been exaggerated by top officials but said it found no evidence that the wrong conclusions were the result of political pressure.
"Tragically, the intelligence failures set forth in this report will affect our national security for generations to come," said Senator Rockefeller.
"Our credibility is diminished. Our standing in the world has never been lower. We have fostered a deep hatred of Americans in the Muslim world, and that will grow. As a direct consequence, our nation is more vulnerable today than ever before." President Bush called it a "useful report" about where the intelligence community "went short". "We need to know. I want to know. I want to know how to make the agencies better," he said.
CIA deputy director, Mr John McLaughlin, who takes over as acting CIA director from Mr George Tenet this weekend, said: "We get it ... we understand with all we have learned since then, that we could have done better."
The report accuses intelligence analysts of falling victim to "group think" assumptions that Iraq had weapons and castigates Mr Tenet for exaggerating evidence and freezing out dissenting views.
It finds no evidence of active co-operation between al-Qaeda and Saddam Hussein, also used to justify the war, and dismisses the claim frequently made by Vice President Dick Cheney that an al-Qaeda activist met an Iraqi official in Prague before the 9/11 attacks on the US.
A US State Department spokesman acknowledged that some material US Secretary of State Colin Powell used to make the case for war at the UN was flawed but that "Iraq wanted weapons of mass destruction" and there was no reason for Mr Powell to apologise.
"Leading up to September 11th, our government didn't connect the dots," Senator Rockefeller said. "In Iraq, we are even more culpable because the dots themselves never existed." He added that it was clear the administration "had made up their mind that they were going to go to war".