The U.S. government's latest National Intelligence Estimate (NIE) has concluded that Iran froze its active efforts to manufacture nuclear weapons in 2003, and will not have such a capability until at least 2012. While the NIE states that the U.S. intelligence community has "high confidence" that the Iranians halted their nuclear weapons program in 2003, it also states that it has only "moderate confidence" that Tehran has not restarted the program.1 In contrast, Israeli Defense Minister Ehud Barak has said that while it is "apparently true that in 2003, Iran stopped pursuing its military nuclear program for a certain period of time," nonetheless, he adds that "in our estimation, since then it is apparently continuing with its program to produce a nuclear weapon."2

This assessment contrasts sharply with estimates that, if left undisturbed, Iran will cross the threshold in the next year or two - and the evidence for the NIE's sweeping claim is unclear. The International Atomic Energy Agency (IAEA) recently confirmed official Iranian claims to have completed construction of the 3,000 centrifuges necessary to produce enough highly enriched uranium for at least one nuclear weapon per year. This is also the basis for the statements from Israeli military and intelligence officials which view the next year - 2008 - as critical for stopping Iran before the finish line.

A number of factors can explain these differences in assessments. Israel, the prime potential target for a nuclear Iran, cannot afford to take the chance of underestimating the threat, and therefore relies on what policy-makers refer to as a "worst-case" analysis. This means that the focus is on Iranian capabilities, rather than intentions, which can only be guessed.

Using this approach, when Iran reaches the technological potential to produce enough fissile material necessary to make a nuclear weapon, it will be considered to be a nuclear weapons state, capable of threatening Israel with annihilation. And while the details of Iran's weapons fabrication efforts can be hidden and are less likely to be known to intelligence agencies, the operating assumption is that there are secret facilities where this may be taking place. Indeed, Israeli analysts have long warned their U.S. counterparts about the potential for a parallel "black" Iranian weapons program, based on a small nuclear reactor producing plutonium, and following the North Korean model. Indeed, Iran is known to be constructing just such a reactor at Arak, leaving room for another undetected facility.

The consequences of a small, secret Iranian nuclear program are less significant for the U.S., given its massive military superiority over Iran. Therefore, there is more room for political factors and influence in the official U.S. estimates. After having warned of a massive Iraqi program to produce weapons of mass destruction in 2003, and then finding no evidence following the invasion, the U.S. intelligence agencies may be trying to restore their image by going to the other extreme and underestimating the pace of Iran's nuclear weapons program. And Iran may very well continue to face difficulties in operating a very complex system of thousands of centrifuges spinning in unison and moving uranium to ever higher levels of enrichment without contamination.

However, from the portions of the NIE report that have been released, it appears that much of the assessment is based not only on technical capabilities and information gathered from satellites and other sources, but rather on attempts to understand Iranian intentions. But intentions are the most unreliable dimension in the realm of intelligence, and often reflect the interests, biases, and expectations of the assessor. While the construction of a massive centrifuge facility at Natanz to produce weapons grade uranium may not be the optimum path to nuclear weapons from an American perspective, this may be the best option open to Iran, and cannot be discounted. The scale and cost of the Natanz nuclear complex, as well as the plutonium production reactor and other facilities are not consistent with a program limited to producing low-enriched uranium for energy production. This makes no economic sense.

The NIE report touches on the Iranian plutonium program: "We judge with high confidence that Iran will not be technically capable of producing enough plutonium for a weapon before about 2015." But the NIE also takes into consideration that such materials might be imported: "We cannot rule out that Iran has acquired from abroad - or will acquire in the future - a nuclear weapon or enough fissile material for a weapon." U.S. arms control experts specializing in North Korea have indeed warned in the past about the scenario of North Korean exports of plutonium products to Iran as a possible shortcut to producing an Iranian bomb.3

Although President Bush responded to the NIE report by reconfirming his determination to prevent Iran from gaining nuclear weapons, the threat of attack from the U.S. in the next five years is now much less credible. Given the disquiet in the U.S. over the status of the situation in Iraq, and with an official assessment stating that Iran gave up its program to develop nuclear weapons four years ago, the president would face very strong opposition to any decision ordering U.S. forces into battle again. And the fear of a potential Iranian counterattack, in the form of mass terror and possible missile attacks against American assets in the region, would increase this opposition.

As a result, a number of Israeli analysts and officials have expressed concern and even dismay over the NIE report and its implications. Israeli officials reject the NIE conclusions, and, as noted, view the threat as far more imminent. If Israeli intelligence concludes that the red lines are closer than those perceived in the U.S., Israel could still use force unilaterally (as was the case in Prime Minister Begin's decision to destroy Iraq's Osiraq reactor in 1981). But Israeli officials have sought to avoid a situation of needing to act unilaterally again.

For Iran, the sudden change in the U.S. assessment contained in the NIE report is a mixed blessing. The good news for the Islamic regime is that the odds of American military action have declined, at least for the time being. Iran can apparently continue to develop its centrifuges and reactors without fear of a sudden U.S.-led attack, and the odds of overt Israeli action have probably also declined.

However, the intense Iranian effort to be seen as a nuclear power that can no longer be stopped has been clearly exposed as a bluff. President Ahmedinejad and other officials have invested heavily in the attempt to portray the Iranian nuclear capability as a fait accompli that must be accepted in the region and around the world. And they have been aided at times by Dr. Mohammed El Baradei, the Director General of the IAEA.

Now, however, the Iranian leadership and an increasingly restless public face at least five more years of sanctions, international isolation, and pressure. And Dr. El Baradei has pulled back from granting Iran immunity from sanctions by highlighting the history of deceit and calling for full cooperation from Teheran. Indeed, following the U.S. report, the leaders of Europe, as well as China and Russia, have reiterated the dangers that would result from an Iranian nuclear weapon capability. Thus, the celebrations in Iran may be short-sighted and short-lived. The economic and diplomatic pressure is likely to continue and even increase.

The bottom line, as noted in the NIE report and by President Bush, is that Iranian nuclear efforts remain dangerous, and that there is still time to prevent this radical regime from acquiring these weapons. How much time remains the subject of debate, and the NIE conclusions are tentative and subject to revision at any time as new information becomes available. To its credit, the NIE report admits the limitations of the U.S. intelligence community with respect to its ability to determine that the 2003 halt in the Iranian weapons program is permanent: "We do not have sufficient intelligence to judge whether Tehran is willing to maintain the halt of its nuclear weapons program indefinitely." Clearly, the NIE conclusions now appearing in the press are not the end of the story.