Aye, there’s the rub
A nuclear deal with Iran is looking more likely than ever before. The P5+1 or EU3+3 (either way it is the US, Russia, UK, France, China and Germany) are making progress on issues related to enrichment and plutonium production and reprocessing. Verifying that fissile material, which can be used in an atomic bomb, is not diverted from those processes is a routine responsibility of the International Atomic Energy Agency (IAEA). If Iran will agree to limits on the number of its centrifuges, the degree of enrichment and the quantity of plutonium produced as well as fulfill its Safeguards commitments, the IAEA can verify that the limits are not exceeded and material is not diverted to a weapons program. If Iran were nevertheless to decide to “break out,” it would require six months to a year for it to do so, leaving time for both diplomatic and military efforts to prevent it from doing so.
The crunch issues lie in a different direction: undeclared nuclear material and the related question of possible military dimensions (PMDs) of Iran’s past nuclear activities. The International Atomic Energy Agency (IAEA) has been making little progress getting from Tehran clarification of past activities that appear to have aimed at design of high explosives and other research on initiation of a nuclear explosion. Nor has it been able to ascertain that there are no nuclear materials lying outside its purview. The IAEA concluded in September (and repeated Friday, despite recent meetings at which PMDs were discussed):
the Agency is not in a position to provide credible assurance about the absence of undeclared nuclear material and activities in Iran, and therefore to conclude that all nuclear material in Iran is in peaceful activities.
In other words, a nuclear deal–even one with tight constraints on known facilities–could leave material and activities unaccounted for that are directed specifically at building a nuclear weapon in secret. Construction activity at a suspected site of clandestine nuclear activities (Parchin) has raised suspicions that Tehran is covering up past nuclear weapons research.
Some would like to forget about Iran’s past misbehavior, which reportedly stopped in 2003 in the wake of the US invasion of Iraq (when at least some in Tehran thought the Americans might come their way next). Ignoring past behavior and the possible existence of undeclared nuclear material would be unwise. Judging from past performance in other countries, development of nuclear weapons is far more likely to take place in parallel, secret efforts than in nuclear plants and activities under IAEA surveillance. If Iran wants the rest of the world to believe that it has seriously and permanently foresworn nuclear weapons, it needs to convince everyone that it either never did have a clandestine program or had one and gave it up.
This is difficult for Iran because of its government structure. President Rouhani is responsible for the nuclear negotiations. But the most likely sponsor of a clandestine nuclear program (past, present or future) is Supreme Leader Khamenei, who controls ample resources for such a purpose, including the Iranian Revolutionary Guard Corps (IRGC). That’s why President Obama writes Khamenei secret letters. The Supreme Leader has reportedly forsworn nuclear weapons in a fatwa:
the production, stockpiling and use of nuclear weapons are forbidden under Islam and that the Islamic Republic of Iran shall never acquire these weapons.
The trouble is Islamic jurisprudence allows a fatwa, which generally has no official written form, to be changed or reinterpreted. This one was published in an official government press release in 2005 that has evaporated from the worldwide web. That does not inspire confidence. So one well-connected Iranian commentator living in the US suggests it be “secularized” as a criminal statute. Of course that could be changed as well, but the notion of getting Iran to pledge formally that it will not seek nuclear weapons could certainly be part of a nuclear deal.
It would not substitute for what some might regard as impossible: proving the negative proposition that Iran does not have clandestine nuclear materials or a clandestine nuclear research program. “Coming clean” about past nuclear activities would certainly help. Continuing to stiff the IAEA on PMDs and the construction (now stopped) at Parchin does not. President Obama is presumably ready to justify to Congress and the American people a nuclear deal with Iran that allows it to continue peaceful activities (including enrichment) under tight IAEA surveillance, but he won’t get far unless he can also persuade them that there are no clandestine nuclear activities in progress. That’s what will give him pause.
PS: Tony Cordesman discusses in detail the difficult issues associated with clandestine research and development for nuclear weapons here.