Iran-U.S. nuclear negotiations in Vienna: Why it’s critical to understand what breakout capacity means.

How a Widely Misunderstood Term Could Doom the Iran Nuclear Negotiations

How a Widely Misunderstood Term Could Doom the Iran Nuclear Negotiations

Events beyond our borders.
June 18 2014 11:54 PM

The Trouble With “Breakout Capacity”

How a widely misunderstood term could doom the Iran nuclear negotiations.

Talks with Iran at the UN headquarters in Vienna.
Vice President of the European Commission Catherine Margaret Ashton and Iranian Foreign Minister Mohammad Javad Zarif attend P5+1 talks with Iran at the U.N. headquarters in Vienna on June 17, 2014.

Photo by Dieter Nagl/AFP Photo/Getty Images

For better or worse—and probably for worse—negotiations to peacefully resolve the standoff over Iran’s nuclear program may hinge on a single technical term: “breakout capacity.”

“Breakout capacity” refers to the time it would take to produce enough highly enriched uranium for a nuclear weapon, should Iran at some point decide to build one. The term isn’t formally part of the negotiations that resumed in Vienna this week between Iran and the P5+1 (the five permanent members of the U.N. Security Council, plus Germany). Rather, negotiators discuss things like how many centrifuges Iran should be allowed to keep as part of a peaceful nuclear energy program. But back in Washington, when people in Congress and elsewhere argue over what constitutes an acceptable deal, they talk in terms of breakout: How much breakout capacity would Iran have if left with a given number of centrifuges, or a given amount of some other variable under negotiation?

It’s a valid question. All the more unfortunate, then, that so many people—including politicians, pundits, and policy analysts—are so confused about it. Some misunderstand the literal meaning of “breakout capacity.” Others misunderstand its practical meaning; they fail to see that how threatening a given “breakout time” is depends heavily on other aspects of a negotiated deal—and so they pay too little attention to those crucial aspects. The result of Washington’s muddled preoccupation with breakout capacity is that negotiations in Vienna may well be heading toward an outcome that damages America’s interests and makes war with Iran more likely.


There are several big issues to be resolved if a deal is to be had by the July 20 target date, but one of the biggest is about centrifuges. Iran has roughly 19,000 centrifuges for enriching uranium, about 10,000 of which are operating, and it has signaled that it won’t accept cuts in that inventory and will eventually need to expand it. How firmly Iran will stick with this position is unknown, but it’s true that Iranian President Hassan Rouhani, like President Obama, has hard-line critics that he needs to mollify, and he can’t afford to be seen by the Iranian people as consenting to Iran’s humiliation.

These 10,000 operational centrifuges, given existing stockpiles of low-enriched uranium, imply an estimated breakout time of two to three months. That’s about twice as long as the estimated breakout time last year, before Iran started reducing its stockpile of medium-enriched uranium in compliance with an interim deal reached in November.

The P5+1 countries, most conspicuously the United States, want Iran’s centrifuge infrastructure to shrink. The exact U.S. negotiating position isn’t known, but various indicators, including statements by former Obama administration officials, suggest a willingness to leave Iran with about 4,000 of its existing centrifuges. That number (depending on other dimensions to be negotiated, such as limits on enriched uranium stockpiles) implies an estimated breakout time of six months to a year.

A big unknown on both sides is negotiating flexibility. How much compromise is acceptable, and at what point do you decide that no deal would be better than the deal on offer? Here is where prevailing American thinking about breakout capacity could damage America’s interests. Before deciding what is and isn’t acceptable in the way of breakout capacity, it would help to understand what the term means, both in the abstract and in the context of these negotiations.


Perhaps the most common misconception about breakout capacity is that it refers to the time it would take to actually build a nuclear weapon. Though Iran’s estimated breakout time is now about two months, if Tehran tomorrow embarked on a headlong effort to build a weapon, the project would take much longer than two months.

Having produced enough weapons-grade uranium hexafluoride, or UF6, for one bomb—the part that would take two months—Iran would need to convert the UF6 to powder form, fabricate the metallic core of the weapon from the powder, develop and assemble other components, and finally integrate the weapons package into a delivery vehicle. Estimates used by the White House have this process taking up to a year, and even the most alarming estimates coming from other sources have it taking several months.

And it’s worth noting that these and other American estimates related to Iran’s breakout speed may have a kind of bias. As a former U.S. official told the journalist Laura Rozen, “What everyone tends to forget is that, when U.S. government and academic experts speak on breakout timelines, they are usually describing a worst-case scenario … where Iran gets everything right the first time around, even if they are completing procedures they have never attempted before.”  

Once a bomb is built, there’s testing to be done. States with nuclear weapons typically conduct multiple test explosions—particularly for the smaller, more efficient designs needed for missile warheads. Eight out of the nine countries that have nuclear weapons openly conducted tests before deployment—and the ninth, Israel, seems to have conducted a clandestine test off of South Africa. Preparing, conducting, and evaluating a test would take months—and would also mean that a new bomb had to be built, since the test would have eliminated the first one.


In short, even if “breakout time,” as conventionally defined, is only a few months, or even a few weeks, what you might call the “effective breakout time”—the time it takes to produce a deliverable weapon—is closer to a year, maybe longer.

That said, it’s true that for some purposes it makes sense to focus on breakout time in the narrow, conventional sense—the time it takes to produce just the uranium for a nuclear weapon, not the weapon itself. In the event that Iran sought to build a nuclear weapon, the United States and Israel have said they would use military force to stop it. And that mission would presumably be most feasible when the material for a weapon was still being produced at known enrichment facilities. So in terms of military tactics, breakout time in the strict sense—the time that is currently estimated as about two months—does matter.

On the other hand, once you start thinking about military tactics, questions arise as to whether there’s much practical difference between a two-month breakout capacity and the American goal of a six-to-12-month breakout capacity. Contingency plans for bombing have no doubt already been drawn up, so, as a strictly military matter, the highest-priority strikes could be initiated within weeks if not days of discovering that Iran was pursuing a nuclear weapon.

Of course, the United States might precede a military strike by trying to amass international support. But there would be virtually no hope of giving these strikes the sanction of international law through U.N. Security Council authorization, because that would require the approval of both Russia and China. If breakout was proceeding, and the only way to disrupt it was to act within weeks, the United States and Israel would act within weeks—illegally, maybe, but decisively. So extending the breakout time from two months to six months wouldn’t have a very clear impact on Iran’s ability to violate the terms of a deal with impunity—and therefore would have little impact on Iran’s incentive to comply with the deal.


One thing that would impact both Iran’s incentives and the American capacity to impede its nuclear breakout is not reaching any deal at all. The above scenario—bombing Iran within weeks of breakout—assumes that U.S. officials would know when breakout had commenced. Right now they have high confidence of detecting breakout because of the monitoring and inspection procedures that were implemented under the November interim deal—and that would be expanded as part of a final deal.

But if there is no deal, and hence no prospect of further sanctions relief, Iran could be expected to return to the weaker monitoring regime that preceded the interim deal or to abandon that regime entirely. Then there might be no way of knowing if or when breakout had started. And, over time, as the Iranian nuclear program evolved in darkness, there would be less and less certainty about the best way to disrupt a dash for the bomb in the event that such a dash became apparent.

In short, a breakout capacity of any duration—two months, six months, whatever—has a very different meaning under circumstances of transparency than under less transparent circumstances. Becoming so focused on incremental differences in breakout capacity as to lose sight of this fact is not in America’s interests.

There’s a second, and related, reason that preoccupation with breakout capacity is misguided. The U.S. intelligence community assesses that, if Iran did decide to pursue a nuclear weapon, it probably wouldn’t do so by using its existing, closely monitored nuclear infrastructure. Rather, Iran would develop secret enrichment facilities and indeed an entire secret weapons manufacturing infrastructure. 


This “sneakout” scenario further underscores the value of reaching a deal with Iran. A final deal is widely expected to include Iran’s acceptance of the “additional protocol” to the Nuclear Non-Proliferation Treaty. That would not only expand the list of “declared” facilities subject to inspection, but would also give international inspectors the right to inspect undeclared facilities that aroused suspicion. This intrusive monitoring would make covert breakout more likely to be detected—and thus less likely to happen in the first place.

As the U.S. intelligence community has consistently noted since 2007, Iran has the scientific, technical, and industrial capacity to eventually produce nuclear weapons if it chooses to do so. Though repeated bombing could disrupt a weapons program, there is no way to reliably stop it short of a ground invasion and long-term occupation. 

So the most realistic goal in Vienna isn’t to make breakout impossible, but to make it a difficult and unattractive option for Iran. Once you see that as the goal, you realize that the gains in transparency from any likely deal—extremely close monitoring of declared facilities and the power to inspect undeclared facilities—should be at the forefront of American thinking about this problem. It would be a mistake to sacrifice such transparency in a failed attempt to reduce Iran’s breakout capacity by some arbitrary increment that is actually less valuable than many in Washington think it is.

A common refrain among U.S. and Israeli officials has been that a bad deal is worse than no deal. Well, yes; since one common definition of a bad deal is a deal that’s worse than no deal, that aphorism is hard to argue with. But the question being begged here is: Which deals would truly be worse than no deal?

The key to answering this question intelligently is twofold: realize that the practical differences among the various deals being seriously discussed in Vienna have been exaggerated by misunderstanding the meaning and implications of “breakout capacity”; and realize that the contrast between the virtues of any of these deals and the perils posed by reaching no deal at all is much starker than is generally appreciated.

Once you see this, you see that there’s little chance of American negotiators signing on to a truly bad deal. The more likely danger is that they’ll turn down a deal that’s much better than no deal.

This article was published in collaboration with the American Foreign Policy Project.