Iran tested advanced nuclear warhead design - secret report
Exclusive: Watchdog fears Tehran has key component to put bombs in missiles
Julian Borger, diplomatic editor
guardian.co.uk, Thursday 5 November 2009 20.45 GMT
www.guardian.co.uk/world/2009/nov/05/iran-tested-nuclear-warhead-design

Short-range missile Zelzal is test launched during war games in Iran.
Photograph: Shaigan/AFP/Getty Images
The UN's nuclear watchdog has asked Iran to explain evidence suggesting that
Iranian scientists have experimented with an advanced nuclear warhead
design, the Guardian has learned.

The very existence of the technology, known as a "two-point implosion"
device, is officially secret in both the US and Britain, but according to
previously unpublished documentation in a dossier compiled by the
International Atomic Energy Agency (IAEA), Iranian scientists may have
tested high-explosive components of the design. The development was today
described by nuclear experts as "breathtaking" and has added urgency to the
effort to find a diplomatic solution to the Iranian nuclear crisis.

The sophisticated technology, once mastered, allows for the production of
smaller and simpler warheads than older models. It reduces the diameter of a
warhead and makes it easier to put a nuclear warhead on a missile.

Documentation referring to experiments testing a two-point detonation design
are part of the evidence of nuclear weaponisation gathered by the IAEA and
presented to Iran for its response.

The dossier, titled "Possible Military Dimensions of Iran's Nuclear
Program", is drawn in part from reports submitted to it by western
intelligence agencies.

The agency has in the past treated such reports with scepticism,
particularly after the Iraq war. But its director general, Mohamed
ElBaradei, has said the evidence of Iranian weaponisation "appears to have
been derived from multiple sources over different periods of time, appears
to be generally consistent, and is sufficiently comprehensive and detailed
that it needs to be addressed by Iran".

Extracts from the dossier have been published previously, but it was not
previously known that it included documentation on such an advanced warhead.
"It is breathtaking that Iran could be working on this sort of material,"
said a European government adviser on nuclear issues.

James Acton, a British nuclear weapons expert at the Carnegie Endowment for
International Peace, said: "It's remarkable that, before perfecting step
one, they are going straight to step four or five ... To start with more
sophisticated designs speaks of level of technical ambition that is
surprising."

Another western specialist with extensive knowledge of the Iranian programme
said: "It raises the question of who supplied this to them. Did AQ Khan [a
Pakistani scientist who confessed in 2004 to running a nuclear smuggling
ring] have access to this, or is it another player?"

The revelation of the documents comes at a time of growing tension. Tehran
has so far rejected a deal that would remove most of its enriched uranium
stockpile for a year and replace it with nuclear fuel rods which would be
much harder to turn into weapons. The Iranian government has also balked at
negotiations, which were due to begin last week, over its continued
enrichment of uranium, in defiance of UN security council resolutions.

There are fears in Washington and London that if no deal is reached to at
least temporarily defuse tensions by the end of December, Israel could set
in motion plans to take military action aimed at setting back the Iranian
programme by force, with incalculable consequences for the Middle East.

Iran has rejected most of the IAEA material on weaponisation as forgeries,
but has admitted carrying out tests on multiple high-explosive detonations
synchronised to within a microsecond. Tehran has told the agency that there
is a civilian application for such tests, but has so far not provided any
evidence for them.

Western weapons experts say there are no such civilian applications, but the
use of co-ordinated detonations in nuclear warheads is well known. They
compress the fissile core, or pit, of the warhead until it reaches critical
mass.

A US national intelligence estimate two years ago said that Iran had
explored nuclear warhead design for several years but had probably stopped
in 2003. British, French and German officials have said they believe
weaponisation continued after that date and may still be continuing.

In September, a German court found a German-Iranian businessman, Mohsen
Vanaki, guilty of brokering the sale of dual-use equipment with possible
applications in developing nuclear weapons. The equipment included
specialised high-speed cameras, of the sort used to develop implosion
devices, as well as radiation detectors. According to a report by the
Institute for Science and International Security, the German foreign
intelligence service, the Bundesnachrichtendienst, testified at the trial
that there was evidence that Iran's weapons development was continuing.

The IAEA is seeking to find out what the scientists and the institutions
involved in the experiments are doing now, but has so far not been given a
response. The agency's repeated requests to interview Mohsen Fakhrizadeh,
whose name features heavily in the IAEA's documentation and who is widely
seen as the father of the Iranian nuclear programme, have been turned down.

The agency has also asked Iran to explain evidence that a Russian weapons
expert helped Iranian technicians to master synchronised high-explosive
detonations.
The first implosion devices, like the "Fat Man" bomb dropped on Nagasaki on
9 August 1945, used 32 high-explosive hexagons and pentagons arrayed around
a plutonium core like the panels of a football. The IAEA has a five-page
document describing experimentation on such a hemispherical array of
explosives.

According to a diplomat familiar with the IAEA documentation, the evidence
also points to experiments with a two-point detonation system that
represents "a more elegant solution" to the challenges of making a nuclear
warhead, but it is much harder to achieve. It is used in conjunction with a
non-spherical pit, in the shape of a rugby ball, or explosives in that shape
wrapped around a spherical pit, and it works by compressing the pit from
both ends.The IAEA has expressed "serious concern" about Iran's failure to
give an account of the research its scientists have carried out.

Descriptions of "two-point implosion" warheads designs have occasionally
appeared in the public domain (there are extensive descriptions on
Wikipedia) and they were first developed by US scientists in the 1950s, but
it remains an offence for American officials or even non-governmental
nuclear experts with security clearance to discuss them.