The most important impact of the NIE's findings is there is no imminent threat. If the NIE is correct (and as we learned with Iraq, intelligence is a sketchy business), Iran does not have and is not currently working to develop a nuclear weapon. Thus, there seems to be no need to contemplate preventive or preemptive uses of military force.
But that does not mean that there is no threat. A careful read of the NIE, or a perusal of this graphic from the New York Times, demonstrates that, at root, there are few real differences between the 2007 NIE and the 2005 NIE that concluded that Iran was trying to develop a nuclear weapon. Both reports assert that Iran will be capable of developing a nuclear device by the next decade: In fact, where the 2005 report claimed that "Iran is unlikely [to make a nuclear weapon] before early-to-mid next decade," the 2007 NIE has repeated that assessment, stating "Iran would probably be technically capable of producing enough highly enriched uranium for a weapon sometime between the 2010-2015 time frame."
Furthermore, the NIE states that while Iran halted its nuclear weapon program in 2003, it qualifies that statement with a footnote saying that "by 'nuclear weapons program' we mean Iran's nuclear weapon design and weaponization work and covert uranium conversion-related and uranium related work; we do not mean Iran's declared civil work related to uranium conversion and enrichment." This is a highly problematic qualification. The US, the EU, and the UN have long considered Iran's civil nuclear program to be worrisome. Given Iran's long history of NPT violations concerning its civilian nuclear program, the international community has viewed Iran's civil nuclear program as a source of concern nearly as great as its potential weapons program. And, as this New York Times article points out, "The open secret of the nuclear age is that the line between civilian and military programs is extraordinarily thin:"
Here, again, the NIE is less than reassuring. It states that it assesses Iran is most likely to obtain HEU through centrifuge enrichment and that "Iran resumed its declared centrifuge enrichment activities in January 2006" and that "Iran made significant progress in 2007 installing centrifuges at Natanz." The 2010-2015 time frame mentioned above is based on estimations of Iran's ability to produce through centrifuge enrichment enough HEU for a nuclear device. Additionally, "Iranian entities are continuing to develop a range of technical capabilities that could be applied to producing nuclear weapons, if a decision is made to do so."
One threshold is enriched uranium. Enriched to low levels, uranium can fuel a reactor that produces electrical power — which is what Tehran says it wants to do. But if uranium is purified in spinning centrifuges long enough, and becomes highly enriched, it can fuel an atom bomb.
Another boundary between civilian and military programs is weapons design. Designing a nuclear weapon involves sophisticated mathematical and engineering work to figure out how to squeeze the bomb fuel in a way that creates the nuclear blast.
Indeed, the most difficult part of building a bomb is not doing the secret military design work but rather the part of the process that is also crucial to civilian nuclear power — producing the fuel.
History illustrates the point. During World War II, scientists working secretly at Los Alamos in the mountains of New Mexico were so sure of the reliability of their simple design that they gave it no explosive test before the bomb was made and dropped on Hiroshima. It worked to devastating effect.
But making the bomb’s highly enriched fuel required a vast industrial effort clouded by great uncertainty. In a race, three huge factories were built in the Tennessee wilds, each pursuing a different way of enriching uranium. One had literally millions of miles of pipes.
In the end, no technique worked well enough to be relied upon exclusively. So engineers blended the outputs. “All three methods contributed to Hiroshima,” said Robert S. Norris, author of “Racing for the Bomb” (Steerforth, 2002), a biography of the project’s military chief.
That history cast light on the question of whether Iran’s enrichment work today could represent a future military threat.
It appears that Iran is going to be walking a thin line, staying on the "good" side of a civilian program, but retaining the ability to cross the line to military applications if deemed necessary.
The real change from the 2005 to the 2007 NIE is in the assessment of Iran's intentions (which is interesting given the caveat in the NIE that the 10 year time frame of the NIE's estimate is "more appropriate for estimating capabilities than intentions....). In 2005, the intelligence community "assess[ed] with high confidence that Iran currently is determined to develop nuclear weapons despite its international obligations and international pressure, but we do not assess that Iran is immovable." [emphasis added] The 2007 judgment essential revises the estimate of Iran's determination, assessing that Iran can be influenced by "increasing international scrutiny and pressure."
If Iran's intentions have changed, but its capability to produce a nuclear device have not changed, then it is just as important as before to maintain "international scrutiny and pressure." Already, rosy readings of the NIE are having their effect as Russia has expressed skepticism at the need to use the threat of expanded sanctions to coax Iran into greater cooperation with the IAEA. While the European states, and France and Germany in particular, have stated their willingness to maintain attention and pressure on Iran, the Russian hesitance highlights the need for a new diplomatic strategy. As I blogged about before, trading the European-based ballistic missile defense program for Russian assistance in forcing Iran to come clean and cooperate is just such a strategy. And the NIE hasn't made a case for a different one.