Samples taken by the U.N. nuclear watchdog at a warehouse in Tehran showed traces of uranium that Iran has yet to explain, two diplomats who follow the agency’s inspections work closely say.
The International Atomic Energy Agency (IAEA) is investigating the particles’ origin and has asked Iran to explain the traces. But Tehran has not done so, according to the diplomats, stoking tensions between Washington and Tehran. U.S. sanctions have slashed Iranian oil sales and Iran has responded by breaching its 2015 nuclear deal with world powers.
In a speech a year ago Israeli Prime Minister Binyamin Netanyahu, who vehemently opposed the deal, called on the IAEA to visit the site immediately, saying it had housed 15 kg of unspecified radioactive material that had since been removed.
The IAEA, which is policing the nuclear deal, had inspected the site – a step it had said it takes “only when necessary” – and environmental samples taken there were sent off for analysis.
Those traces were, however, of uranium, the diplomats said – the same element Iran is enriching and one of only two fissile elements with which one can make the core of a nuclear bomb. One diplomat said the uranium was not highly enriched, meaning it was not purified to a level anywhere close to that needed for weapons.
“There are lots of possible explanations,” that diplomat said. But since Iran has not yet given any to the IAEA it is hard to verify the particles’ origin, and it is also not clear whether the traces are remnants of material or activities that predate the landmark 2015 deal or more recent, diplomats say.