Samples taken by the U.N. nuclear watchdog at what Israel's prime minister called a "secret atomic 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.