Iran has begun enriching uranium with a fourth cascade, or cluster, of advanced IR-2m machines at its underground Natanz plant, a report by the UN atomic watchdog showed, in a further breach of its 2015 nuclear deal with world powers.
It was the latest of many steps by Iran raising pressure on U.S. President Joe Biden with the two sides in a standoff over who should move first to salvage a deal that was meant to curb Iran's ability to develop a nuclear bomb, if it so intended.