Iran has begun enriching uranium at its underground Natanz plant using a cascade of advanced centrifuges, the latest breach of a 2015 nuclear deal with world powers.

The Vienna-based International Atomic Energy Agency (IAEA) said on March 17 that two days earlier, Director General Rafael Grossi informed member states that Iran is now using faster IR-4 centrifuges to enrich uranium hexafluoride up to 5 percent purity.