Mr Negroponte said: "[Iran] seems to be determined to develop nuclear weapons.
"We don't have a clear-cut knowledge but the estimate we have made is some time between the beginning of the next decade and the middle of the next decade they might be in a position to have a nuclear weapon, which is a cause of great concern." Mr Negroponte also acknowledged that US intelligence had made mistakes assessing the weapons capabilities of Iraq before the invasion, but said lessons had been learned and corrective measures taken.