Given that both Iran and North Korea are pursuing nuclear weapons capabilities in defiance of UN mandates, it would seem logical for the two outlaw programmes to share their respective know-how. After all, each is prevented by UN sanctions from legally acquiring the material and technological wherewithal needed to develop nuclear weapons that can be reliably delivered.
With a long history of bilateral cooperation in the development of ballistic missiles dating back to the late 1980s, it would not be hard for Pyongyang and Tehran to put those well-practised trade deals and transfer routes to use in the nuclear-weapons field. It is therefore a mystery why the world has seen few signs of nuclear cooperation between the two charter members of the rogue nation club. It is not for lack of looking. Western intelligence agencies are intensely targeting nuclear acquisition efforts by Iran and North Korea. More than 90 states have signed the US-led Proliferation Security Initiative that is designed to interdict nuclear and missile-related trade to and from those two regimes.
Yet finding nuclear weapons-related trade is akin to the proverbial needle in a haystack. In the vastness of ocean and sky routes, most forms of nuclear-related cargo are so minute as to be almost undetectable. Moreover, nuclear weapons work in any country is conducted with utmost secrecy. UN expert panels set up to monitor the implementation of sanctions have explained the ways in which Tehran and Pyongyang evade sanctions by using intermediaries in China and long-distance cargo aircraft. The UN panels have documented several instances of missile-related illicit trafficking between Iran and North Korea but nothing about nuclear trade.
Comparing the two nuclear programmes, it is striking how they have developed in different ways. Both have explored the two pathways to nuclear weapons: highly enriched uranium, as was used in the bomb dropped on Hiroshima, and plutonium, which formed the fissile material for the Nagasaki bomb. Yet, whereas Pyongyang went the plutonium route for the devices it tested in 2006 and 2009, Iran has emphasised enriched uranium.
More recently, North Korea also appears to have given priority to the enrichment route - witness the shiny gas centrifuge facility it proudly displayed last November. Among the interesting aspects of that facility is that the centrifuges, of second-generation vintage, were made of maraging steel, a high-strength material that is difficult to manufacture. By contrast, although Iran acquired the same second-generation centrifuge designs from Pakistani black marketeer AQ Khan, it chose to use carbon fibre. Iran cannot manufacture maraging steel and has already used most of the stock that it acquired before western countries clamped down on trade in this material. If there were nuclear cooperation between the two countries, it would be logical for North Korea to sell Iran maraging steel and for their centrifuges to look more alike.
The media coverage of Iran-North Korea nuclear cooperation has usually been based on unidentified intelligence sources. Unsubstantiated claims include the alleged presence of Iranian scientists at Pyongyang's 2006 nuclear test and a 2005 Reuters report of North Koreans lecturing during a specialist nuclear training course in Tehran. Last December, Mohammad Reza Heydari, who defected from his diplomatic post in Oslo earlier in 2010, said that from 2002 to 2007, when he headed the foreign ministry's office for airports, he saw many North Korean technicians arriving to collaborate on the Iranian nuclear programme.
In an April 2008 background briefing, however, US intelligence officials flatly denied an Iranian-North Korean nuclear connection. There is no doubting the presence of North Korean technicians in Iran who provide assistance for ballistic missiles and learn from Iran's own testing and development work. Given the secrecy of Iran's nuclear weapons-related activities, it is unclear how Mr Heydari would have been able to conclude that the North Koreans were involved in nuclear-related work rather than ballistic missiles. Throughout the past eight years, even senior Iranian negotiators have repeatedly been surprised by new revelations about Iran's nuclear activities.
Late last month, two new reports of a North Korea-Iran nuclear connection emerged. On August 24, the Munich-based Sueddeutsche Zeitung said North Korea had in the spring delivered dual-use US software that could simulate neutron flows. The unclassified computer programme has many civilian applications, but its export is strictly controlled because it can be used to calculate chain reactions for the development of nuclear explosives. A North Korean delegation reportedly travelled to Iran in February to train 20 defence ministry employees in the software. The newspaper vaguely attributed its information to western intelligence sources. And on August 26, an article published in Israel collected various strands of information to suggest that Iran may have financed the North Korea-Syria deal to construct a plutonium-producing reactor near the town of Deir Al Zour (a site also known as Al Kibar), which Israel bombed in September 2007.
Like the previous reports, neither of the latest stories is confirmed. They should not be dismissed out of hand, however. The well-credentialed Sueddeutsche is no tabloid and the information it reported is generally consistent, at least in terms of developmental level, with other reports that the International Atomic Energy Agency has assembled about what strongly appears to be nuclear weapons-related work by Iran. The IAEA's extensive reports on Iran's nuclear programme, however, have never mentioned anything about a North Korea connection.
In sum, I am less sceptical about the evidence of an Iran-North Korea nuclear connection than I was several months ago. But confirmation is needed before anyone can draw any conclusions.
Mark Fitzpatrick is the director of the Non-Proliferation and Disarmament Program at the London-based International Institute for Strategic Studies and the editor of Strategic Dossiers on Iran and North Korea