Iran has taken a significant new step toward possible atomic-weapons production, starting work on an assembly line to manufacture a key material used at the core of nuclear warheads, the United Nations atomic agency said in a confidential report Wednesday, raising the stakes in Tehran’s standoff with Washington ahead of President-elect Joe Biden’s inauguration. The International Atomic Energy Agency, in a report for member states… – Wall Street Journal Photo: Tasnim News Agency via Wikimedia Commons. CC BY 4.0. Cropped