By Adam Entous
The timeframe comes as President Barack Obama presses a reluctant China to back swift sanctions on Iran and U.S. intelligence agencies try to finish a classified report assessing how Tehran's nuclear program is progressing.
Jane Harman, chairwoman of the U.S. House of Representatives Homeland Security Subcommittee on Intelligence, told Reuters on Tuesday that a revised U.S. National Intelligence Estimate (NIE) on Iran was "essentially complete" but that it was unclear if any of it would be made public after going to the president.
Western powers fear Iran wants to develop nuclear weapons under the cover of a civilian atomic program. Tehran says its program is intended only for peaceful power generation.
U.S. General David Petraeus, who as head of Central Command overseas wars in Iraq and Afghanistan bordering Iran, said Tehran's nuclear ambitions have sent ripples across the region, and that the United States was "quietly" beefing up the "defensive preparations" of key allies there.
He told a Washington conference that while a lack of progress settling the Arab-Israeli conflict has long been cited by Arab leaders as their biggest concern, "Iran, I think, is now edging that issue out."
Opinions within the U.S. intelligence community vary on the extent to which Iran's nuclear capabilities have changed since the release in November 2007 of a declassified summary of the previous NIE on Iran by then-President George W. Bush.
That 2007 document judged with "moderate confidence" that Iran would "probably" be technically capable of producing enough highly enriched uranium for a weapon sometime in the 2010-2015 time frame.
The current view within the intelligence community is that Iran would be capable of producing enough highly enriched uranium for a weapon in the "next few years," closer to 2015 than 2010, though officials cautioned that such timetable have been proven unreliable.
TECHNICAL 'PROBLEMS'
To explain the delay, U.S. officials in recent months have pointed to what they have described as technical "problems" at Iran's enrichment plant at Natanz in operating thousands of the centrifuges that have been installed.
Asked about reported comments that Iran might be able to join the nuclear club in months, Defence Secretary Robert Gates told reporters on Tuesday: "I don't believe it."
"I think that most estimates that I've seen, haven't changed since the last time we talked about it, which is probably at least a year, and maybe more," he said.
Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, continues to hold that Iran will have a capability to build a weapon in one to three years, according to aides.
Israel, which is believed to have the Middle East's only nuclear arsenal, sees an Iranian warhead by 2014 and believes a prototype may only be "months away."
U.S. officials, speaking on condition of anonymity, said final touches on a revised National Intelligence Estimate could take weeks or months, and voiced doubt that President Barack Obama would release a declassified version as then-President George W. Bush did in 2007.
The office of the Director of National Intelligence would neither confirm nor deny that an NIE was being prepared.
Harman said intelligence suggesting that Iran's nuclear development may be delayed was no reason for the international community to hold back on tough sanctions.
"There are two coordinates — one is their intention and one is their capability — and both of them have to be assessed. Our operating assumption should be that debilitating sanctions need to be pursued now," he said.
(Additional reporting by Phil Stewart; editing by Vicki Allen)
