At such level, uranium is a relatively short jump from weapons-grade material; signatories to nuclear deal have urged Tehran not to squander chance to salvage the 2015 accord

UN atomic watchdog head says additional understandings must lay out how Iran's violations of multilateral accord can be reversed, as parties are no longer at 'square one'

France, Germany and UK say announcement by Tehran violates nuclear deal, reiterate commitment to 2015 pact

Proposal, days after top nuclear scientist was assassinated, requires several more votes to become law; lawmakers chant 'Death to Israel' during session

Students affiliated with Basij paramilitary group hold small protest outside foreign ministry in Tehran; some call to expel IAEA inspectors in response to assassination

IAEA says Tehran is using advanced technology at underground Natatz plant prohibited by 2015 nuclear agreement with world powers

IAEA says Tehran has added over 300 kilograms of low-enriched uranium since late August, is also enriching at greater purity than permitted under 2015 pact

Atomic watchdog says Islamic Republic's explanations are 'not credible,' demands answers on activity at Tehran warehouse dating back to early 2000s

IAEA says centrifuge structure meant to replace Natanz plant hit by mysterious explosion over summer; Tehran had promised to replace site with more secure one in mountains

IAEA says it took environmental samples from location following agreement last month that ended standoff over suspected activity