You know, the burning question is, and it has been asked by Rush Limbaugh just a couple of weeks ago, "do we want to fight the Iranians before or after they have nuclear weapons?" Because war with Iran is a question of when not if.
I have made the point repeatedly on this site that Iran has been at war with us since the fanatical shia coup of 1979. The problem for us, is that they have been aggressive and we have been on the receiving end. They violated international law by allowing the "students" (Mahmoud the Mad was one of them) to seize our embassy in Teheran. They sacked the place like the Huns sacked Baghdad in the 1200's. They incarcerated and tortured our embassy staff for 444 days. They were instrumental in providing the support to the hezzies to kill over 200 Marines in Beirut back in 1983. There are many more examples of incidents which in my mind provide for a casus belli.
In sum the West cannot allow a terrorist state such as Iran, actually the epicenter of world terrorism, to acquire nuclear weapons. A messianic martyr complex with nukes is a dangerous thing.
A small point--it was the Mongols who sacked Baghdad in the 1200's.
(An incident which should give us hope: until the Mongols dealt with them, the Shi'ite Seveners, or Ismaelis, were the most viscious and bloodthirsty of Mohammedans, fielding the Assassins against Sunni, Shi'ite Twelver, and Christian alike. After their defeat by the Mongols, they went peaceful: Seveners are mostly well-educated professionals in Pakistan now, and are among the most pacific of Muslims.)