The International Atomic Energy Agency reported new evidence that Iran has undertaken activities relevant to the production of a nuclear weapon, some of which may be ongoing.  The evidence came from more than ten countries and from independent sources.  According to the IAEA report, Iran created computer simulations and built a testing site to study how conventional explosives can be used to trigger a nuclear device.  The report also says that Iran may have sought uranium for an undisclosed enrichment program, obtained nuclear explosive design information, and explored a number of missile warhead designs suitable for delivering a nuclear payload.  Iran has rejected the report's findings.