The International Atomic Energy Agency (IAEA) was confirming Iranian reports of Tehran's step, taken in retaliation for the agency's criticism of Iran in a board of governors resolution last week.While Iran is already enriching uranium up to 60% purity elsewhere, its decision to do so at Fordow is likely to be viewed by Western nations as particularly provocative because the site is buried under a mountain, making it harder to attack.The latest move is in retaliation to last week's resolution by the IAEA's 35-nation Board of Governors ordering Iran to cooperate with the agency's years-long investigation into the origin of uranium particles found at three undeclared sites.It was summarising a confidential report to IAEA member states seen by Reuters on various moves taken and planned by Iran at enrichment plants at Fordow and Natanz.In the longer term, however, Iran plans an expansion of its underground, commercial-scale Fuel Enrichment Plant at Natanz, where it is also installing and bringing online more cascades of advanced centrifuges."