The United Nations' top nuclear inspector says there's been progress recently but that many questions remain over allegations that Iran pursued a nuclear weapons program.
Tero Varjoranta, chief inspector for the International Atomic Energy Agency (IAEA), was speaking one day after Iran agreed to take new steps to increase the transparency of its atomic activities.
In particular, the IAEA said Iran has agreed to provide information about its "need or application for the development of Exploding Bridge Wire detonators."
The IAEA says these detonators can have non-nuclear uses but mostly are used in weapons research and so Iran's reported development of them is a concern.
The IAEA probe is separate from the nuclear negotiations Tehran has been holding with world powers.
Iran has consistently denied any pursuit of nuclear arms.
Based on reporting by Reuters, AP, and AFP