A large group of Iranian nuclear scientists and technicians has been spotted in the last few days at North Korea's nuclear center at Yongbyon, according to DEBKAfile's intelligence sources. American and South Korean watchers assumed at first they were examining the new, extra-fast centrifuges for enriching uranium North Korea had showed off to America visitors in November. But they thought again when a small group broke away from the Iranian delegation for a secret side-trip to visit North Korea's Punggye-ri testing site near the Chinese border and appeared to be receiving detailed briefing on the next nuclear test planned soon by Pyongyang.

US and South Korean intelligence experts now strongly suspect now that they were putting their heads together for making it a joint North Korea-Iranian test.
One South Korean intelligence source reported that the Iranian visitors brought with them a large sum of money, estimated at least at $150 million, in all likelihood to cover Pyongyang's fee for staging a nuclear test on Tehran's behalf. French intelligence subscribes to this assumption in view of the dramatically heightened interchanges between North Korea and Iran in the last two months.
On Dec. 2, DEBKAfile disclosed that French President Nicolas Sarkozy had strongly urged US President Barak Obama to get tough militarily with North Korea – not just over the crisis in the peninsula but for fear Pyongyang would use the sound and fury to distract attention from its transfer to Iran of nuclear technology and advanced centrifuges for offsetting the malfunctions retarding its progress towards a weapon.
Sarkozy argued too that Tehran has decided to engage the world powers in talks on its nuclear program – the second round takes place in Istanbul this month – solely to play for time until North Korea's assistance kicked in.

It is now believed in Paris that Tehran and Pyongyang have brought their plans forward. Instead of going through the process of shipping nuclear items and materials from North Korea to Iran and risking their interception by American forces in keeping with international sanctions, they have decided to go straight for a joint nuclear test to be carried out at the North Korean testing site. This step would defeat the enforcement of international sanctions.

This possibility was suggested in one of the remarks Gen (ret.) Moshe Yaalon, Deputy Prime Minister with portfolio for Strategic affairs, made on the subject on Dec. 29: "Iran does not currently have the ability to make a nuclear bomb on its own," he said. The "technical difficulties" he referred to (without specifying who or what had caused them) had disabled Iran's independent nuclear weapons capability, he said, implying that they did not stand in the way of Tehran's ability to call on outside help for attaining its objective.
DEBKAfile: North Korea is the only outsider with the ability and will to help Iran.

Taken with other remarks, Yaalon's words were interpreted as conveying the following message to Washington: We've dealt with Iran; it's your turn to take care of North Korea and make sure they don't outmaneuver us by using Pyongyang's nuclear facilities to fill in the gaps for Iran.
That would include conducting a nuclear test on Iran's behalf as its subcontractor or surrogate.