Britain's special representative to Iraq has admitted the coalition forces "misanalysed" the situation in the country both before and during the war.
Greenstock: Don't expect a smooth passage to peace in Iraq
In a BBC interview Sir Jeremy Greenstock, who ends his role on Saturday, also warned there would be no easy route to lasting peace in Iraq.
He admitted the process of transition from occupation to Iraqi sovereignty had not gone perfectly to plan.
But he insisted democracy remained "a distinct possibility".
Sir Jeremy told the BBC's correspondent in Baghdad, Caroline Hawley: "We misanalysed at the beginning, both before and during the conflict."
He had always championed the need to bring affairs in Iraq back to the control of Iraqis as soon as that was sustainable.
Before leaving for Iraq just over six months ago, Sir Jeremy said he saw his role as supporting that of US administrator Paul Bremer.
He had agreed to take on the job after his formal retirement at the age of 60 from the Foreign Office,
In his previous role, as the British ambassador to the UN,
Sir Jeremy issued the statement in March 2003 ruling out a further resolution on military action in Iraq.