In the first chapter of "The Inheritance," David Sanger talks about Iran's nuclear program and sheds light on some misconceptions we have.

In 2003 a secret US intelligence report concluded that Iran had suspended work on designing a nuclear weapon. It leaked to the public, and it undercut the Bush Administration's call for sanctions against Iran. Why were we contemplating military action against Iran when they had halted their program? Other countries already felt we had misled them about Iraq (which we had), so there was no trust factor. Instead, they wondered if we were on the verge of another Iraq. 

But that was misleading. Sanger notes that designing the bomb is the easy part. It can be done late in the process, and done quickly. The hard part is gathering the parts needed (like centrifuges) and enriching enough uranium (which can be part of the civil nuclear energy program). "The Iranians," Sanger wrote, "had halted their work on the final step, the physical construction of the weapon." 

It's like accumulating all the ingredients to make a cake. You just don't figure out the specifics of the recipe--how much of this, how much of that, what temperature to bake at--until you're ready to start. An experienced cook can figure out that part quickly.

Japan doesn't have nuclear weapons, and they aren't trying to develop them. But everyone agrees they could probably do it overnight if they wanted to. They have everything they need (especially the technical expertise). 

That's where Iran may be. The info about Iran suspending their weapon design program is misleading.