So, according to a recently published NIE, Iran's nuclear program was halted in 2003. Most are discussing the question, why has the US been all over them if they don't have anything? I think an equally, if not more important question is, why has Iran's President been acting defiant and insisting on his country's right to nuclear arms, if they are not developing any? It would be one thing if he had been vehemently denying the nuclear program, only to be proved right. But he seemed more convinced of the program's existence than President Bush.
Here's my theory, though it may be out there - Ahmadinejad saw this as a unique opportunity to act like a bully, primarily towards Israel. It's easier to threaten a neighbor when you have a significant deterrent capability, which Iran obviously does not. It also might have led Iran to feel more comfortable supporting insurgents in Iraq, thinking that the US and others were afraid of their capabilities.
If this was the case, Ahmadinejad almost brought his country complete destruction at the hands of the US and Israel, who were afraid of the possibility of a nuclear Iran, and would have done anything to stop such a situation. On the whole, though, the entire situation is inexplicable, and makes no sense from either side. Something tells me that we're not done with this issue.