We are always planning for war, with a lot of countries, it doesn't mean we are going to do it.
As for striking at Iran's nuclear facilities, they have learned a lesson from Osirak (obiviously the Syrians did not). There facilities are said to be spread around the country in a wide variety of locations, some are rumored to be well hidden and dug in. Would it be impossible to strike them really hard? No, but it would present a targeting problem that would make it very difficult to ensure that we would deliver a knockout blow to their nuclear program, assuming that is the primary target.
Even if we were able to successfully strike the Iranian regimes nuclear programs, they have deep ties to several very dangerous and capable terrorist organizations, namely Hezbollah. They have struck repeatedly at Israeli targets all over the world, and are responsible for the deaths of over 300 US citizens. They retain unique capabilities among terrorist groups in the world, and would be able to make multiple and wide-ranging terror attacks spanning the globe in response to an attack on their sponsor and patron, Iran. They demonstrated their formidable conventional capabilities in the 2006 war in Lebanon, where they fought Israel on the open battlefield and acquitted themselves well (with some unintentional help from the Israelis). And they are not a despised dictator that few in the Arab public care for like Saddam was, they are widely renowned as heros on the 'Arab street' for standing up to Israel and in their eyes, 'winning'. They, like everyone else, like a winner and there have been few and far between in the Arab world against the Israelis.
Should this completely deter us from attacking if neccessary? No, but we should be fully aware of the consequences. That is something that I don't think the American public is aware of, or even most of the people on this board.
And while many of you here might dispute the point, our credibility around the world has been seriously damaged by the war in Iraq. Our arguments about the nuclear threat in Iran suspiciously sounds a lot like our discredited argument about Saddam's WMD. That is not to say that Iran's program is peaceful, but where is the beef? Even our most steadfast allies, Australia and Britain, would likely not support us in strikes against Iran. Prime Minister Brown is already on shaky political ground and facing elections within the next two years. Prime Minister Rudd, while still a strong ally, is not the unabashed cheerleader of the US that Prime Minister Howard was, and is very lukewarm to Iraq.
So, are we really willing to strike Iran alone and unafraid, with little public support both at home and abroad, just months before we get a new President? A country with almost twice the population and almost 4 times the size of Iraq when our forces are already stretched in Iraq and Afghanistan? I hope not......