And although Washington has shown unwavering conviction that war against Saddam Hussein was right, recent comments by US leaders hint that they recognise a growing problem.
Secretary of Defense Donald Rumsfeld surprised many in the US Senate Wednesday by testifying that when the Pentagon went to war, it did not have weapons of mass destruction on its mind.
"We did not act in Iraq because we have discovered dramatic new evidence of Iraq's pursuit of weapons of mass murder," Rumsfeld told a senate subcommittee.
"We acted because we saw the existing evidence in a new light through the prism of our experience on September 11," he said, referring to the 2001 terror attacks in the United States that killed some 3,000 people.
His testimony effectively swept aside the government's arguments put to the United Nations and the international community for invading Iraq: the threat of an attack on the United States.
That drew cries of "irresponsible" from arms control experts, including Daryl Kimball, head of the Arms Control Association.
Greg Thielmann, a former head of the State Department's Bureau of Intelligence and Research, said: "The Bush administration did not provide an accurate picture to the American people of the military threat posed by Iraq."
He added: "Some of the fault lies with the performance of the intelligence community, but most of it lies with the way senior officials misused the information they were provided."
And Thielmann said the administration's attitude toward intelligence on Iraq had been "faith-based." In other words, "We know the answers, give us the intelligence to support those answers."
An increasing number of experts said that intelligence on Iraq did not always match the facts, especially on its nuclear arms.
Some say the United Nations dismantled Iraq's nuclear program after Saddam's armies were repelled from Kuwait in 1991.
The White House formally admitted this week that President George W. Bush should not have said in his January 28 State of the Union address that Iraq had tried to purchase enriched uranium in Africa to relaunch its nuclear weapons program.
Several analysts also believe that shortly before the war started on March 20, Baghdad had no missiles capable of reaching Saudi Arabia or Israel.
"Intelligence is not evidence," said Gregory Treverton, a former vice chairman of the National Intelligence Council, which produces US security evaluations.
"The Bush administration has turned intelligence into evidence."
For Joseph Cirincione, director of the Non-Proliferation Project, a Carnegie Endowment think-tank, said that given the fact that UN inspectors turned up nothing in the final months of their work on top of the US troops' inability so far to find the weapons shows that Bush went too far out on a limb.
"The administration went far beyond the intelligence assessments in changing those assessments," he said.
Still, on April 10, White House spokesman Ari Fleischer said he was convinced that Iraq had such weapons.
"We have high confidence that they have weapons of mass destruction. That is what this war was about and it is about."