Months after Bush warned of "World War III" or a "nuclear holocaust" if the Islamic republic gets nuclear weapons, the NIE cited "high confidence" that Tehran had halted its nuclear weapons programme in late 2003 and "moderate confidence" that it had not restarted as of mid-2007, the AFP news agency reported.
'Open options'
At the same time, the Islamic republic is "keeping open the option to develop nuclear weapons," according to declassified key findings of the report, which was based on intelligence available as of October 31.
"But we do not know whether it currently intends to develop nuclear weapons," according to the estimate.
According to the declassified key findings, Iran is likely to be capable of producing enough enriched uranium for a nuclear weapon "sometime during the 2010-2015 time frame".
The report found that "the earliest possible date" Iran could have enough highly enriched uranium for a weapon was late 2009, "but that this is very unlikely".
But the White House has urged global powers to "turn up the pressure" on Iran.
'Serious problem'
Stephen Hadley, a national security adviser, said: "The intelligence ... tells us that the risk of Iran acquiring a nuclear weapon remains a very serious problem.
"The bottom line is this: for that strategy to succeed, the international community has to turn up the pressure on Iran - with diplomatic isolation, United Nations sanctions, and with other financial pressure - and Iran has to decide it wants to negotiate a solution," he said in a statement on Monday.
"The estimate offers grounds for hope that the problem can be solved diplomatically - without the use of force - as the administration has been trying to do," he said.
Iran denies Western charges that it seeks nuclear weapons under cover of a civilian atomic energy programme, and has drawn UN sanctions for refusing to freeze its uranium enrichment, which can yield materials for a nuclear bomb.
Meanwhile, Mahmoud Ahmadinejad, Iran's president, said that the issue of Tehran's controversial nuclear programme was "closed" and that his country was prepared for any eventuality.
"The nuclear issue is now closed. We do not feel threatened at all and we are prepared for any eventuality or conditions," he said during an annual summit of the Gulf Co-operation Council (GCC) Qatar's capital, Doha.