What Will It Take to Go To War With Iran?

I searched for a thread on Iran's thwarted plot to assassinate the Saudi ambassador to the US in Washington, but could not find one. I find this surprising so if there is already a thread up and running on this topic, i would appreciate directions.

In any case...

News reports on the discovered Iranian plot were often accompanied by the comment that the mere fact that such an act was planned could be considered an act of war by the US (not to mention the Saudis), and certainly if it had gone off as planned the matter would have been even more critical.

Because the plot appears to have been somewhat amateurish, there has been a lot of speculation that it was never actually developed by the Quds Force, and would not have been known to, let alone approved by, the Supreme Leader, Ayatollah Ali Khamenei.

Yet the Administration insists that intelligence strongly supports the notion that the plot was approved at the highest Qud levels. This morning in an interview with Chris Wallace, Senator Dianne Feinstein (D), Chairwoman of the United States Senate Select Committee on Intelligence confirmed that the intelligence is solid.

Assuming the plot was the brainchild of the Qud Forces a number of Iranian "experts" voice the opinion that the Supreme Leader would have known about it.

Whether through fine intelligence efforts, a bumbling execution of the plot, or some combination of both, the assassination didn't happen. If it had, it is believed likely that explosives would have been used which of course would have created the possibility of a number of injuries and fatalities in addition to the Saudi targets.

As often seems to be the case with thwarted plots (and particularly those that involve some degree of bumbling) the matter has been somewhat downplayed, certainly in comparison to how it would have been treated if there was a smoking ruin in DC where a restaurant once stood and ten or eleven American citizens were dead, along with the Saudi Ambassador and his retinue.

Obviously the existence of the plot is not being considered by the US government as an act of war on the part of Iran but what if the scenario described above had taken place? What do you think the US government's response would have been and should have been?

Certainly, if Saudi Arabia didn't previously consider themselves to be at war with Iran, they should now.

The Saudis have interests all over the world and their ambassadors are not the most vulnerable to attack in the US, and so I think we have to assume that the DC location was not coincidence or convenience, but a key intentional element of the design.

Iran has been killing Americans in Iraq and Afghanistan for some time. In July the Treasury Dept announced it had formed a strategic partnership with al-Qaida. It is the primary backer of both Hamas and Hezbollah, and it has been exporting terrorism around the region and the world for years. What's more, the regime has shown it is capable of the very same acts of violence against its citizens that prompted NATO and the US to invade Libya.

And...it is developing nuclear weapons.

Existing sanctions and the threat of stricter ones don't seem to have warned the Iranians off of attempting something as outrageous and provocative as this plot, and so it seems almost seems inevitable that there will be some sort of military faceoff between the US and Iran within the next 5 years.

Do you agree, and if so care to predict roughly how soon from now and in response to what particular action?