Crucial aspects of Iran's nuclear program remain a puzzle to the outside world, and Tehran prefers to exploit uncertainty about whether it has begun building an atomic bomb, analysts said Monday.

On Sunday, the head of the CIA said Iran had enough uranium for two nuclear bombs, which could be ready to be launched in a weapon as early as 2012, a forecast experts said was in line with most outside assessments.

But spy chief Leon Panetta left open the key question of whether Iran had opted to begin assembling an atomic bomb, saying it was a matter of debate inside the regime.

"Nobody knows if Iran has taken this decision," said Sharon Squassoni of the Center for Strategic and International Studies.

"It's more in their interest to have this ambiguity."

US and European intelligence agencies have struggled to nail down details of Iran's nuclear capabilities and plans, and Tehran has used the uncertainty to its advantage.

The ambiguity has divided intelligence experts, delayed or softened international action against Tehran in recent years and helped ward off possible military action by the United States or Israel, analysts said.

"It's a little tricky to predict when they may make a decision," Institute for Science and International Security chief David Albright told AFP.

"But right now, I don't think it's in their interest to make a decision to build the bomb, because they're still too vulnerable to having that program disrupted by military strikes."

If it chose to produce highly-enriched uranium for a bomb, Iran at the moment would have to rely on its centrifuge plant in Natanz, which could be hit in an Israeli or US air strike.

Iranian officials have suggested they are planning a secret enrichment site, and at one point said construction work had already begun.

Washington, however, has yet to uncover official efforts inside the regime to oversee the manufacture of warheads, said Albright, a physicist who tracks clandestine nuclear programs.

Panetta's comments about Iran's nuclear program coincided with growing speculation US spy agencies are revising an earlier estimate that Tehran suspended work on building atomic weapons.

"The US seems to be shifting on the question of -- is Iran working on nuclear weaponization?" said Albright.

A 2007 National Intelligence Estimate under former president George W. Bush concluded that Iran had halted work on assembling a warhead around 2003, while British, French and German spy services found Tehran later resumed its weapons work.

"I've been hearing for months that it (the new US estimate) will be closer to the European view," said Albright.

"It's been tricky to come up with agreed upon language. They don't want to look like they're reversing their decision" from 2007, he added.

Neither the United States nor its top regional ally Israel, the sole if undeclared nuclear-armed power in the Middle East, have ruled out a military strike to curb Iran's atomic drive.

Despite mounting international pressure over its uranium enrichment work and a new round of UN Security Council sanctions adopted this month, Iran vehemently denies charges it is pursuing nuclear weapons.

The Iranian leadership increasingly views the nuclear program as "an issue of national and ideological importance," said Alireza Nader, an analyst at the Rand Corporation.

Amid internal unrest and a troubled economy, the Iranian regime sees the nuclear program as a way of trumpeting national progress, he said.

"The nuclear program could be seen not just as a distraction but as a mark of success," Nader added.

earlier related report
Dialogue over nuclear fuel swap to continue: Iran
Tehran (AFP) June 29, 2010 - Iran said on Tuesday that its decision to freeze talks with world powers for two months relates only to its overall atomic programme and does not include discussions on a nuclear fuel deal.

Moscow meanwhile said that Russia, France and the United States have asked the UN atomic watchdog to organise a meeting with Iran over the fuel deal on condition Tehran halts its 20 percent uranium enrichment programme.

Iranian Foreign Minister Manouchehr Mottaki told reporters the issue of Iran's nuclear programme is separate from that of a proposed swap deal that would ensure a fuel supply for the Tehran research reactor.

President Mahmoud Ahmadinejad on Monday ruled out talks with the P5+1 world powers -- Britain, France, Russia, China, the United States and Germany -- on Tehran's nuclear programme until the end of the Iranian month of Mordad, around late August.

Asked at a news conference Tuesday whether the freeze declared by Ahmadinejad includes discussions on the fuel swap deal, Mottaki replied: "The question of Mordad is (only) about the five-plus-one.

"Negotiations about the fuel swap are only about the fuel swap and negotiations with five-plus-one are about the common points of the proposed packages... these two things are separate," he said.

The six world powers have offered to talk with Iran about its nuclear programme, especially its uranium enrichment drive, which they want halted fearing it is aimed at making weapons. Tehran strongly denies the allegation.

But Ahmadinejad said on Monday that the UN Security Council's decision on June 9 to impose a fourth set of sanctions against Iran for refusing to halt the uranium enrichment work had made talks impossible in the short term.

"We are postponing the talks because of the bad behaviour and the adoption of the new resolution in the Security Council. This is a penalty, so that they (the world powers) are disciplined to learn the way of talking to other nations," he said.

He, however, said that Iran was ready to talk on the fuel deal but did not clarify whether these discussions would be held in the next two months.

Iran has been separately engaged since October in talks with the US, Russia and France and in recent weeks with Brazil and Turkey over the nuclear fuel deal for the Tehran research reactor.

The US, Russia and France -- part of the so-called Vienna group -- have sent a list of questions to Iran regarding the latest version of the fuel deal which was proposed by Iran, Brazil and Turkey on May 17.

Mottaki said "the answer to the letters sent by the Vienna group is being prepared" and stressed Iran has been discussing the May 17 proposal with Brazil and Turkey.

The deal stipulates that Tehran will send 1,200 kilograms of its low-enriched uranium (LEU) to Russia and France to be supplied at a later date with 20 percent high-enriched uranium for the Tehran reactor.

"There have been contacts and communication between foreign ministers (of Iran, Brazil and Turkey) last week and we have concluded that this course should continue," Mottaki said.

Russian Foreign Minister Sergei Lavrov said that the US, France and Russia have asked the International Atomic Energy Agency to arrange a meeting with Iranian experts over the fuel deal.

But he said the meeting was sought "under the understanding that Iran itself halts the 20 percent enrichment."

"I expect Iran to respond constructively because it will allow us to settle the situation that generates concern," Lavrov said Tuesday.

Turkey also called on Iran and Western powers to implement the fuel deal soon.

"If they do not sit down and talk, we will be in a worse-off situation this time next year. Time is working against a solution," Turkish foreign ministry spokesman Burak Ozugergin said.

"President Ahmadinejad alluded to the month of August (for the talks). We wish they would take place sooner," Ozugergin said.

World powers have been infuriated after Iran began producing 20 percent enriched uranium since February.

Mottaki said Iran's production of 20 percent enrichment uranium was need based.

"Producing 20 percent enriched uranium is not something that countries do continuously. We have this capacity to produce today. When we need it, we produce it and when we don't need it, we don't produce it," he said.

Enriched uranium is at the heart of Iran's controversial nuclear drive as the material when refined to more than 90 percent level can be used to make atomic weapons.