Former US President Jimmy Carter has said the Iraq war was one of the "greatest blunders" ever made by a US leader.
Carter however, said on CNN he believed the raging sectarian violence wracking the US-occupied country so far fell short of a civil war.
"I think that the original invasion of Iraq, and all of its consequences, yes, were a blunder," Carter said.
"It's going to prove, I believe to be one of the greatest blunders that American presidents have ever made."
Asked whether the Iraq war would prove to be a bigger mistake in the annals of US foreign policy than the war in Vietnam, he answered: "I think it is going to be a close call ...
But perhaps much more vividly known by the rest of the world than Vietnam was."
The former president, who served from 1977 to 1981, said, however, President George W Bush could still navigate a way out of Iraq that could be defined as a victory, by agreeing to an international conference on the conflict.
Carter also added his voice to the semantic debate on how to describe the fighting, saying he did not think it amounted to the kind of civil war in which his Carter Center human rights foundation had intervened.
"I think a civil war is a more serious circumstance than exists in Iraq," he said, but added that it was not really important how the conflict was described.
Bush, during a visit to Latvia for the NATO summit, earlier sidestepped suggestions Iraq had sunk into civil war, arguing that a recent upsurge in violence was part of a spiral of sectarian unrest that began nine months ago.