According to the doctrine of pre-emptive war, Iran can be attacked based on its alleged desire to develop nuclear weapons, just as Iraq was attacked in 2003. In fact, Congress is currently debating whether a nuclear capability alone (which Brazil, Japan, and other countries enjoy) could justify the 'preventive' attack. I believe it is time to negate this doctrine by postulating that Iran in fact has a right, as a sovereign nation, to a nuclear capability.
Having traveled to Iran recently, I can attest to the Joint Chiefs' General Dempsey's reference to Iran as a 'rational' actor. The Iranians have no interest in destroying America, or Israel, at the expense of one of the oldest continuous civilizations in the world, dating back about 2600 years. Iran is currently surrounded by over 40 U.S. military installations, not counting Israel's still-unaccounted nuclear arsenal. To assert that Iran would jeopardize its culture for a one-shot nuclear attack is a complete miscalculation of the Iranian spirit; that spirit gave rise to a revolution in 1979 against what they perceived as Anglo-American imperialism in the form of the Shah, much as our own revolution opposed British imperialism.
I agree with General Dempsey that an attack on Iran would not only be imprudent, it would be 'destabilizing', and for more than just Iran. What is at stake is much larger than Iran's right to become a nuclear power; and based on the attitude of the political figures I spoke with in Iran, they understand this very well -- should Israel, with or without American support, attack Iran's nuclear or military infrastructure, it would be considered an act of war that may prompt World War III.
What I believe is currently being played out is an 'endgame' scenario, by failing West European and American economies, threatening to explode what has historically been referred to by British imperialists as the Heartland of Eurasia: stretching from the Horn of Africa (guarding the shipping lanes of the Gulf) to Afghanistan and Pakistan (in Russia and China's underbelly). The Russians know this 'Great Game' well, having played it with the British since at least the Crimean War of the mid-19th Century. So when Russia says it cannot accept the ongoing destruction of the Syrian government, or an attack on Iran, it is based on the understanding that such destabilization of this 'Heartland' could ignite war between Shia and Sunni Muslims across the region, even affecting the Muslim populations of southern Russia and western China.
Iran is currently accused by the West of being a rogue state involved in spreading amorphous terrorism abroad. In reality, Iran has seen the destruction of the sovereign states in Afghanistan and Iraq, on its borders; and now, the Obama Administration is calling for the downfall of Iran's ally, President Assad's secular Syrian regime. That country is quickly going the way of Lebanon in the 1980s, which could reignite sectarian violence from Lebanon to Iraq, and beyond. The chaos ensuing the overthrow of Assad will not only serve to radicalize the religious factions, as the Iraq war did after the fall of the secular Ba'ath Party, but such a strategy seems to have been predicted; retired General Wesley Clark reported in his 2003 book that the imperialist 'neo-con' faction within the U.S. Defense Department had plans for regime change in Iraq, Syria, Libya, Somalia, Sudan, Lebanon and Iran, dating back to before Sept. 11.