Iran, in a fresh rebuff of demands that it abandon its nuclear ambitions, has decided to process a large quantity of uranium into a precursor ingredient used in making both commercial nuclear fuel and nuclear weapons, the U.N. atomic watchdog agency said yesterday. The International Atomic Energy Agency, in a confidential report, said Iran intends to convert more than 40 tons of uranium into uranium hexafluoride (UF 6 ) gas, an intermediate step in the complex process of making enriched uranium. The plan, if carried out, would represent a significant step forward for Iran’s nuclear program and — in the view of Bush administration officials — a growing threat. In theory, that much uranium could yield as many as five crude nuclear bombs. Full Story