First, Iran always claimed that its nuclear program is peaceful and that it has the right to civilian nuclear energy. Iran ratified the Nuclear Nonproliferation Treaty (NPT) in 1970, and since February 1992 has allowed the International Atomic Energy Agency (IAEA) to inspect any of its nuclear facilities. Prior to 2003 no IAEA inspections had revealed Tehran's violations of the NPT. Iran's nuclear program was supported by a lot of contries around the world, including USA in the early time. Some offers was made to Iran to help in his civilian nuclear program and in 1993, Iran and Russia signed an agreement for the construction of Russian reactors at Bushehr. The thing is, all experts are explaining that it's very easy to develop nuclear weapons when you control the art of producing civilian nuclear energy. But the possession of nuclear reactors is not a proof of having nuclear military intentions. For example, a lot of nuclear capable states such as Japan or Canada are using nuclear technology only for civilian purpose.

bushehr russian reactor
Russian VVER-1000 Reactors at Bushehr.

But, even if Iran plans to have nuclear weapons - and it's probable that the mullahs want nukes - it's not a problem for me. I find that the Non-Proliferation Treaty is a total stupid thing. Why some countries should have the right to possess nuclear weapons and not the others? Who are USA, Russia, France, UK and China to tell their neighbours what to do? When USA and Soviet Union started to developed their first nuclear weapons in the 40's, they opened a Pandora's box. Hesiod's myth said "ἀλλὰ γυνὴ χείρεσσι πίθου μέγα πῶμ' ἀφελοῦσα - ἐσκέδασ'· ἀνθρώποισι δ' ἐμήσατο κήδεα λυγρά. - μούνη δ' αὐτόθι ᾿Ελπὶς ἐν ἀρρήκτοισι δόμοισιν - ἔνδον ἔμιμνε πίθου ὑπὸ χείλεσιν" [1]. Since this treaty, some new countries have developed those weapons, such as Israel, India, Pakistan or North Korea. Why not Iran? In my view, the best thing to fight against nuclear proliferation is to start nuclear disarmament, that is undeployment and dismantling of nuclear weapons. Plus, Iran has many foreigners with nuclear weapons: Israel, Russia, India, Pakistan and China.

I don't know if the claim of USA about iranian weapon is right. It could be a pretext to fight against Iran, such as weapons of mass destruction were for Iraq invasion. Iran is not in Bush's so-called "axis of evil." for nothing. Since many years, Iran are deriding USA. And for USA, Iran is the big uncontrolled area in Middle-East. Why? United states have militar basis all around, in Afghanistan, Azerbaidjan, Bahrain, Georgia, India, Iraq, Koweit, Kyrgyzstan, Oman, Qatar, Saudi Arabia, Tadjikistan, Turkey, Uzbekistan. So the power in Middle-East is in the hands of USA, Israel and Iran. If Iran had nuclear weapon, it would change all geopolitical influences in this area, and USA will lost a part of is power.

[1] Which means: "But the woman took off the great lid of the jarwith her handsand scattered, all these and her thought caused sorrow and mischief to mankind. Only Hope remained there in an unbreakable home within under the rim of the great jar". As you can see, Pandora's box is not a box but a jar :-)

Note: Thanks to Sholeh & Dawood.