In the last 6 years or so, there have been literally dozens of official reports about Iran's nuclear program, and virtually all of them have stated that there is no evidence that Iran is planning to develop a nuclear weapon.
What Iran is doing is attempting to achieve a "nuclear capability", which the Iranians claim is for peaceful purposes, like nuclear power plants etc. The problem is that once a country achieves this "nuclear capability" there is little to stop them from using that capability to produce a nuclear weapon.
