The current Iranian régime is, no doubt, corrupt and repressive, in the grip of religious obscurantism. (If that alone were justification, would we have to invade Utah?) Nor is Iran friendly to the United States.
The current of madness, apparently epitomized by the current President Ahmadinejad, is particularly dangerous because of their imminent belief in the return of the Mahdi or Messiah, which might be provoked by chaos on earth.
Probably they are working on a nuclear bomb, and some of them would like to drop it on Tel Aviv or New York, no matter how many Muslims they kill. They were certainly willing to use their children as human minesweepers in their war with Iraq.
No reason to love or trust these folks, and every reason to be wary of them.
That said, I'm not joining the current drumbeat for a military adventure in Iran in the immediate future. I'm for a Kissingerian overture to them for a pragmatic reconciliation, and only if that clearly fails, would I consider the military option. I say this not because I love Iran, but because I believe that we need to think in terms of national interest.
Geopolitically, there is no reason for Iran and the U.S. to be enemies. Unlike a Russia become resurgent, Iran cannot dominate Eurasia, or even more than a part of the Muslim world. At the most, it could extend some influence to Shiite areas of Iraq and Arabia, and to South Lebanon and Syria. The numerically dominant Sunnis are probably immune to anything more than a flirtation with a Shi'a dominated country such as Iran.
Moreover, except in case of apocalyptic events, Iran's economic viability depends on oil exports. Oil being a fungible product, it doesn't matter whether they sell it to us or other buyers--the market effect is the same.
Moreover, although playing a double game, Iran has to some extent been helpful to our efforts in Afghanistan and Iraq, although no doubt soon they'd like our troops further from their borders.
Having experienced Islamism in all its medieval glory, the ancient, civilized nation of Persia has become sympathetic to the U.S. and things Western, notwithstanding the mullahs' strictures.
As a consequence, notwithsanding our residual outrage over the embassy seizure, which Jimmy Carter botched, and our dismay at the sacrifice of youth and clerical repression, we have no foreign policy differences with Iran than can't be compromised. Conclusion--we should be engaged in secret or semi-secret diplomacy to seek a rapprochement with Iran.
The outlines of a settlement are clear--Iranian renunciation of nuclear arms ambitions, American renunciation of military action against Iran. Restoration of diplomatic relations and trade, including oil sales on reasonable terms. Resolution of the dispute over seized Iranian property in the U.S. The usual sorts of international exchanges--delegations, students, wrestlers. Private guarantees against Israeli action against Iran and Iranian attacks on Israel through surrogates such as Hezbollah. Iranian noninterference in the establishment of régimes in Iraq and Afghanistan that would not threaten Iran but would be independent, after which the U.S. military presence should be minimized.
None of this is any more onerous for us than Nixon's deal with China, which has proven to be a major success (although whether China's ascent to great power status will continue smoothly without major difficulty remains to be seen). None of it threatens the U.S.
A process like this would not be easy, and it would not go down well with various sorts of ideologues. But it is in the best interest of this country, and probably of Iran.
The alternative would be miliary conflict, probably requiring a draft in this country, in support of which we would have difficulty achieving national unity. I do not think that a nice "surgical" bombing campaign would be sufficient, and it would solidify support for the mullahs, at least for a time. An invasion is not in the cards, and would not be easy. Without partial mobilization, including a draft, it might fail, or lead to a prolonged, unpopular war. Although in some warped neo-Wilsonian sense, a case can be made out for such an adventure, it would not be in our national interest at all. Less so than the Iraq War, where Saddam was an archvillain even compared to most Middle Eastern tyrants.
If we must go down the military road, let it be after a sustained private or semi-private diplomatic effort.
What about Israel, and Ahmadinejad's bluster about obliterating it? The answer is twofold.
First, notwithstanding Bush's ill-considered statement he would defend Israel against Iraq, Israel has its own deterrent, including nuclear submarines, and has not asked the US for more than diplomatic support and money, as opposed to troops. Israel has always aimed at a degree of military self-sufficientcy. If we negotiate for a resumption of an inspection régime, and reconciliation slowly begins, that process will afford some protection against apocalyptic rashness in Iran, perhaps more than a few airstrikes would do.
Second, there is a serious question as to whether our close bond with Israel is important to our national interest, other than a general interest in avoiding the military extinction of nominal democracies and our client states. Nixon thought protecting Israel was important when the Soviet Union had allied itself with Israel's enemies, but absent a Cold War situation, our mutuality of interest with Israel has sharp limits. Israel often ignores U.S. interests in favor of its own.
Given that a rapprochement between the US and Iran would not critically affect israel, unless Iran managed to cheat on nukes and then ignored the very substantial risks of retaliation, the Israel factor should not impede such an overture.