Speaking to Canada's Sun News, Carnegie's Mark Hibbs explained that if Iran wants a nuclear weapon, it has to do three things. First it has to make fissile material for a bomb; second, it has to make sure that the fissile material explodes exactly in the way they need it to do; and finally, Iran needs a delivery system to make the device an effective nuclear weapon.

"All these things are not trivial," Hibbs said, but "we know that Iran has been making the enriched uranium fuel, and they continue to do this." A report that came out this week speculates about how much of the needed fissile material Iran has, could make, and how it wants to use the material.

Hibbs pointed out, however, that it remains to be seen how much of the explosive work Iran can do or carry out to actually take nuclear material and make it into an explosive device. "It is a highly contentious issue," Hibbs said, adding "some evidence in the hands of the International Atomic Energy Agency explores this issue."

The concern for many people, Hibbs concluded, is the possibility that Iran still has undeclared, clandestine activities which no one knows about. "We don't really know much about what activities Iran has carried out outside of the declared activities."