18 TheEconomistJune 29th 2019
1T
he facility30km (19 miles) north-west
of the Iranian city of Natanz looks like a
humdrum industrial site. Only the anti-
aircraft guns hint at what goes on eight me-
tres (26 feet) underground. For over a de-
cade Iranian scientists there have fed ura-
nium hexafluoride into centrifuges that
spin at twice the speed of sound so as to sift
out uranium-235, the isotope capable of
sustaining a chain reaction in a nuclear
power plant or bomb. The “raw” uranium
that goes in is 0.7%^235 U; the stuff that
comes out is 4%^235 U.
In 2015, as part of the nuclear deal be-
tween Iran, the permanent-five nations on
the unSecurity Council and Germany, Iran
promised that it would not enrich any ura-
nium beyond this 4% level, nor hold stocks
of more than 300kg of such low-enriched
uranium (leu). But in May 2018 President
Donald Trump walked away from that deal,
reimposing old sanctions and adding a
spate of new ones, too. America now im-
poses over 1,000 sanctions on Iran and par-
ties that might trade with it. These sanc-
tions have hurt Iran a lot: inflation isexpected to reach 50% this year, and gdpto
shrink by 6%.
Iran hopes that if it does, or threatens to
do, things others would rather it did not, it
might have its plight relieved. So in May it
quadrupled the rate at which it was produc-
ing leu. On June 27th, according to the In-
ternational Atomic Energy Agency (iaea),
the leustocks at Natanz had not quite sur-
passed 300kg. But in just a few days the
limit could be broken.
An imminent step beyond the limits of
the deal is not a cause for immediate alarm.
For one thing, no amount of leucan in it-
self be used to make a bomb; that is typical-
ly done with uranium enriched to 90% or
so. For another, the step is easily reversed.
Enrichment is difficult, but dilution is a
doddle.
At the point when it signed the deal,
Iran had amassed a much larger stockpile
of leu—ten tonnes—and had many more
centrifuges up and running. Its breakout
time—the time it would take to produce
enough fissile material for a single bomb—
was a harrowing two to three months. Withthe stockpile and centrifuges it has work-
ing at Natanz today, the breakout time
would be over a year.
Stepping over the leu threshold is a sig-
nal that Iran is no longer willing to abide by
the terms of the deal, despite encourage-
ment to do so from the other five parties,
unless it is offered new incentives. Further
steps look sure to follow. Iran’s president,
Hassan Rouhani, recently warned that if
the deal’s other signatories did not set
about easing the country’s economic pain
by July 7th, the country would start enrich-
ing uranium beyond the 4% level. Another
reversible move, but a more troubling one.
Enrichment follows the rules of geometric
growth, so uranium enriched to 20% is
most of the way to 90%.
Other escalations might include: pull-
ing mothballed centrifuges out of storage
to increase the amount of enrichment it
can do; restarting enrichment at Fordow,
an even deeper-buried and thus harder-to-
bomb plant. Perhaps the most ominous
would be to expel the inspectors from the
iaea who closely monitor Iran’s nuclear fa-
cilities, leaving the world blind to any at-
tempts at breakout.
For the time being, Iran is more inter-
ested in hinting at such options than dash-
ing nuke-wards. Measured and reversible
steps lessen the backlash from European
states, which have some sympathy with
Iran’s predicament, and make it harder for
America or Israel to justify a preventive
war. But they are still provocative, andThe narrowing gyre
An unwanted war is not necessarily an unlikely oneBriefing America and Iran