A helpful Reuters piece pulls together the evidence that Iran is, in the words of one, “keeping the soup warm but they are not cooking it,” on weaponization of nuclear capacity. Money quote:
Reuters has learned that in late 2006 or early 2007, U.S. intelligence intercepted telephone and email communications in which Mohsen Fakhrizadeh, a leading figure in Iran’s nuclear program, and other scientists complained that the weaponization program had been stopped. That led to a bombshell conclusion in a controversial 2007 National Intelligence Estimate: American spy agencies had “high confidence” that Iran halted its nuclear weapons program in the fall of 2003.
Current and former U.S. officials say they are confident that Iran has no secret uranium-enrichment site outside the purview of U.N. nuclear inspections. They also have confidence that any Iranian move toward building a functional nuclear weapon would be detected long before a bomb was made.