With tension rising over Iran’s nuclear program, we asked three prominent nuclear experts -- Chaim Braun, Alexandre Debs and Philip Taubman -- to discuss what U.S. policymakers should bear in mind as they consider their range of options. 

Keep an Eye on Enrichment

The major transition from weapons capability to outright capacity will not occur overnight, and there are several insights into this process that the U.S. and its allies should try to identify. Among them: attempts to increase uranium enrichment levels beyond 20 percent.

While there may be some minimal justification to enrich uranium to this level as fuel material for the Tehran Research Reactor, now that Iran claims it could fabricate fuel elements for this reactor there is no justification except for a military purpose to enrich beyond this level. Uranium enrichment to military level could be performed at a specially configured cascade in the new underground Fordow enrichment center or can be performed in a clandestine cascade located elsewhere. In either case, this will require Iran to openly break out from its Nonproliferation Treaty obligations and remove all international safeguards seals under which its 20 percent enriched uranium is kept. This will be a very overt and clear indication of Iran's military intentions, likely to be undertaken only when all other preparations are completed.

Because the International Atomic Energy Agency safeguards inspectors visit the Fordow site only once every several months, Iran could get a good head-start by starting such an enrichment program after the last inspectors visit, temporarily blocking the IAEA on-site cameras and hope such activity will remain hidden at least until the next scheduled inspectors visit.

I should say that several knowledgeable experts believe that Iran has a parallel clandestine enrichment program not subjected to international safeguards where its putative stockpile of highly enriched uranium is produced. For this assumption to be credible, an independent supply of natural uranium will have to be made available beyond what is currently known of the Iranian uranium mining capabilities. Either way, any insight regarding Iranian's intentions to further enrich their uranium to military grade, or the existence of a working clandestine parallel uranium enrichment program, would be an indication of the final Iranian push to acquiring nuclear weapons capacity.

-- Chaim Braun, CISAC consulting professor

We can handle a nuclear Iran

Some analysts fear the consequences of a nuclear Iran and press for a preventive attack. Yet the consequences of a nuclear Iran are manageable. Recent research shows that nuclear superiority is strongly correlated with success in foreign crises. As a result of its nuclear and conventional superiority, the United States could deter a nuclear Iran and could convince its allies that they do not need their own nuclear deterrent. At the same time, a strike against Iran can hardly be limited and effective, given the size of the Iranian program. A strike on Iran would send the wrong message, telling Tehran that Washington fears its nuclearization and that it should quickly acquire the bomb.

The United States should learn the lessons of the nuclearization of North Korea. The U.S. then decided against a preventive strike on Pyongyang because it believed it could contain a nuclear North Korea, and realized that the costs of a preventive war would be high. Doubting U.S. capabilities, and pressing for an attack on Iran, would bring about the worst outcome.

-- Alexandre Debs, Stanton Nuclear Security Fellow and an assistant professor of political science at Yale University

For more on Iran from Debs, see "The Flawed Logic of Striking Iran," a response in Foreign Affairs to an essay by former CISAC fellow Matthew Kroenig arguing that a "carefully designed attack against Iran's nuclear program would spare the region and the world from an unacceptable threat."

Tehran may be playing the "nuclear card"

One of the key questions about Iran is whether it will be content to settle for a nuclear weapons program that stops just short of creating the weapons themselves. If Iran is seeking the international and regional clout -- the intimidation factor -- that comes with owning a nuclear arsenal, it can get much of that just by being on the verge of making warheads. Indeed, Tehran has already expanded its influence by building a nuclear complex that can quickly be enhanced to produce weapons. Stopping short of making weapons might well avoid an Israeli or American military strike and would limit international criticism of the Iranian program, while still giving Iran the means to muscle its neighbors.

My hunch is that developing a small arsenal will be irresistible for the Iranians, but during a visit I made to Iran some years ago, I noted that a number of Iranians officials understood that playing the nuclear card effectively did not require becoming a nuclear weapons state.

-- Philip Taubman, CISAC consulting professor and author of The Partnership: Five Cold Warriors and Their Quest to Ban the Bomb (2012)