Understanding Iran's Nuclear Breakout Options
In the UN General Assembly on October 1, Israeli prime minister Benjamin Netanyahu described Iran's strategy as to retain “sufficient nuclear material and sufficient nuclear infrastructure to race to the bomb at a time it chooses to do so.” In general, there are three main conditions that will need to be present in order for Iran to develop a nuclear weapon. First, Iran would need the technical capacity to produce a critical mass of the uranium isotope U-235 (about 25 kg of uranium enriched to 90%) or the plutonium isotope Pu-239 (about 8 kg of weapons-grade plutonium), develop a detonation mechanism, and a delivery method. Secondly, Iran would need to make a political decision to militarize the nuclear program. And third, no external actor must succeed with halting, delaying or destroying the nuclear program with neither military nor other means. The U.S. and Israel are the only two countries that have signaled willingness to conduct a military operation against Iran's nuclear program.
Given the first two conditions, one critical question should be examined to derive Iran's strategy to “race to the bomb at a time it chooses to do so”: How can Iran reduce the probability that a military operation would succeed (or even undertaken) after it has made the decision to break out for the bomb?
Iran can reduce the expected time frame between when the militarization process begins and when a nuclear bomb is produced, thereby reducing the time available to the International Atomic Energy Agency (IAEA) and Western intelligence agencies to detect the militarization and for political decision makers to undertake actions to stop it. Iran can reduce the time frame needed to acquire critical mass of enriched uranium to a minimum by stockpiling a large amount of uranium enriched to a level of near 20% and install more advanced and effective centrifuges. A small time frame would also have an internal effect on the Iranian decision-making and decision-undertaking. When the time from breakout to bomb is large, it is difficult to keep knowledge of the breakout secret within a limited group. It would then be time available for oppositionists in the regime (or workers at the facilities) to mobilize against the decision (or alert external actors). The opposite would be the case when the time frame is limited.
A successful Israeli military operation would in part rely on the ability to achieve surprise. However, since an Israeli operation might be triggered by the breakout itself, Iran would be able to dictate the terms. By reducing the time needed to produce critical mass of enriched uranium and coordinate the breakout with a larger military exercise, Israel's ability to achieve the element of surprise would be reduced—and Israel would thus have an incentive to launch an attack before the breakout.
Iran can also reduce the utility of an intervention by finishing the heavy-water reactor in Arak and start operating it. A fully operational plutonium-producing reactor would be a politically sensitive target for any interventionist, since the civilian—and thus political—costs of bombing such a reactor would be quite large. If a military operation would leave the Arak reactor intact and only focus on the three other critical facilities in Natanz, Fordow and Isfahan, Iran could use the reactor for producing material for a nuclear bomb in the aftermath of the attack. In practice, this means that if a military operation is to be deployed, it should be conducted before the Arak reactor is operative. The attack on the Syrian al-Kibar reactor was reportedly triggered by similar concerns. Given the prize of achieving the immunizing effect of an operative reactor, Iran might be willing to temporarily suspend the enrichment program (or part of it) if a military intervention seems probable. In particular, a negotiated agreement where Iran is required to suspend its enrichment activity in Natanz and Fordow might be acceptable for the regime as long as the construction of the heavy water reactor in Arak is allowed to continue. An agreement of this kind might also provide Iran with more time to continue possible research concerning a detonation mechanism, warhead design, and delivery method. However, an interventionist would have an incentive to launch an attack before the reactor is operational, which means that its start-up date might trigger an operation against the other facilities as well. Iran's strategists are probably thinking hard about how to make the reactor operative without anybody finding out until after its start-up date.
Iran would have an incentive to delay the construction of a reprocessing facility. Such a facility would be necessary to extract plutonium from the fuel rods used in the reactor. Iran has currently no known such facility with the capability to serve the Arak reactor, but would have an incentive to construct it after the reactor has gone critical. Constructing it now would just cause unnecessary friction with Western countries due to its probable military purpose.
Iran would also have an incentive to delay the breakout if it expects new defensive military means to be acquired or developed within a certain time frame. New acquisitions would increase Iran's general defensive capacity, thereby reducing an interventionist's ability to achieve a successful military operation. Iran has previously voiced its interest in the Russian-made S-300 anti-aircraft battery, though the Russians chose to halt the transfer of the system. Iran could be expected to delay the breakout if Russia would signal renewed interest in transferring this system or similar ones.