The Iranians are aware that, as the U.S. Director of National Intelligence noted in March 2013, they "could not divert safeguarded material and produce a weapon-worth of HEU before this activity is discovered." As long as this is the case, the risk of a sudden, undetected "break out" to the bomb is low.
4. How else might Iran get the bomb in 2013?
Knowing that that any attempt to "break out" to a bomb using its declared facilities would be discovered and interrupted decisively by the U.S. or Israel, Iran's leaders are certain to have considered alternatives. The next path they must have considered is to "sneak out" using secret, undeclared facilities.
We should remember that Iran's current declared enrichment facilities were previously secret -- until they were exposed by foreign intelligence services. Had they not been discovered, one or both of them could already have produced the HEU for Iran's first bomb. Many argue that Tehran must be wary of constructing further secret facilities, fearing that it could be caught by foreign intelligence services yet again. But it is certainly possible that they have done so and thus have an additional path to the bomb.
The defining differences between the "break out" scenario on which most observers focus, and the more likely "sneak out" option are two. First, in breaking out, Iran would take actions that "break the glass," sounding an alarm; in sneaking out, it would create a fog of confusion beneath which it would divert LEU or MEU to a secret site for further enrichment. It has been suggested, for example, that Iran could stage an explosion that releases radioactivity at Natanz, blame Israel for an attack, declare the area quarantined to inspectors and, under this cover, move LEU or MEU. Second, sneaking out requires a secret site to which the material would be moved and where centrifuges would produce HEU that would be shaped into uranium metal and used for a bomb.
Table 5 reminds us that in addition to building a bomb, overtly or covertly, there is a third possible path to a bomb.
Iran could buy one. As former Secretary of Defense Robert Gates famously said, North Korea has demonstrated its readiness to "sell anything they have to anybody who has the cash to buy it." Unfortunately, North Korea has already established a precedent for such a deal. It sold Syria a plutonium-producing Yongbyon-style reactor that would by now have produced enough plutonium for Syria's first bomb -- if Israel had not bombed it in 2007. If the Iranian Supreme Leader concluded that nuclear weapons were the only way to guarantee the survival of his regime, buying a bomb for a billion dollars could be an attractive bargain.
Are such scenarios very likely in 2013? No. Are there technical reasons why either could not occur? No.
5. How has the U.S. attempted to prevent Iran's acquiring a nuclear bomb?
For the past decade, the principal strategy followed by the U.S. government under both Republican and Democratic administrations has been to declare demands: Iran must not do A; Iran will not be permitted to do B (after Iran has done A); Iran cannot do Z. Despite the limits of a "strategy" that consists essentially of repeating one's demands, this remains an American favorite.
In addition, the U.S. has led an effort to impose economic pain on Iran through sanctions. Initially, these were largely symbolic. In the past two years, however, the U.S. and key allies have begun taking actions that are actually biting (see Tables 6 and 7).
If one believes what one reads in the papers, the program of sanctions has been complemented by a series of covert actions including cyberwar or cyber-sabotage that included Stuxnet, Duqu, and Flame, assassinations of key scientists in the Iranian nuclear program, and unnatural explosions at key Iranian missile and steel plants.
6. Is a deal that stops Iran short of a bomb possible? Is it possible to identify the terms of a deal that would be better for both Iran and the United States than either attacking Iran or acquiescing in an Iranian bomb?
My answer is unambiguously yes. Having been engaged in sustained consultations with U.S. government policymakers on this issue for most of the past decade, I can identify at least two occasions on which, viewed simply from the perspective of the recognized national interests of both parties, there seems to me to have been a zone of agreement. In 2003-2004, after the U.S. had toppled Saddam in three weeks without breaking a sweat, Iran feared that it might be next and appeared eager to accept an arrangement in which its enrichment activity would be constrained to a single cascade and subject to full transparency. Since 2009, the U.S. and Iran have been circling around potential terms of an agreement that would cap all enrichment at 5 percent; stop expansion of facilities for enriching to 20 percent; swap current materials enriched to 20 percent for fuel assemblies for the Tehran Research Reactor (TRR); provide maximum transparency; and include credible threats to impose catastrophic costs on Iran if the agreement were violated. Each time an agreement appeared within reach, however, one or the other inserts yet another demand or consideration that scuppers the deal.
Imagine that this issue today were given to Metternich and Talleyrand in 1815, or Kissinger and Zhou Enlai in 1972. They would find reaching agreement easier than the negotiations they concluded successfully.