Iran has long insisted its program is peaceful, though it is the only non-nuclear-armed nation enriching uranium at that level. The U.S., the IAEA and others say Iran had a nuclear weapons program up until 2003.

The clash over Iran's nuclear program is escalating, with U.S. sanctions and Europe's snapback threat putting Tehran under maximum pressure.

Iran's foreign minister is planning a call with French, German, and British counterparts to avoid U.N. sanctions over its nuclear program