If you have been following the news lately, the situation in Iran seems to be slowly but surely heading towards conflict. How the US could be considering entering another war zone with the economy the way it is and the overall war fatigue is beyond me. What is even more ironic are the reasons. The immediate provocation seems to be Iran's nuclear weapons program. Admittedly there are a lot of countries who are going to be uncomfortable with Iran possessing Nuclear weapons, but nobody really expects that Iran has the US in its cross hairs.
For all its failings the Iranian government is not the Al-Quaeda. They have a lot to lose. They are not about to sacrifice their entire population to take a shot at the US. Any attempt to acquire nuclear weapons is at best an effort to stave off invasion ala Iraq.
Can Israel be just as confident that they wont be attacked? Probably not. Even though Israel does not acknowledge possessing nuclear weapons, its widely believed that they are in possession of nuclear weapons. Iran too expects retaliation, should they attack with nuclear weapons.
Any pre-emptive strike on Iran to eliminate its nuclear assets is unlikely to succeed, unlike Iraq in the 80's , Iran will in all likelihood be well prepared.
Sure Ahmedinijad acts crazy, but its unlikely he is doing anything more than playing a part. He is not the be all end all in Iran's polity.
If you took an opinion poll of US analysts on whether the US faced more of a threat from an Iranian nuke or a Pakistani one, I speculate, you might find that most would consider a 'stolen' Pakistani nuke a bigger threat. Iran and Al-Quaeda are natural enemies both due to the Sunni Shia divide and due the Persian-Arab rivalry. There was every chance to exploit this , but it has not been. In international politics there are no permanent friends .. its time the US re-examined its choice of friends.