Actually Shira has a point but it is'nt the whole story.
The "Oil Thing".....
Lets face it, a big part of our "National Interest" in Iraq is their oil. You can't ignore the second largest untapped oil reserve in the world while being the world's biggest dependent on foreign oil.
But it is'nt about 'controlling' their oil, its about market access to their oil.
Point 1:
We were, pre-invasion / post 9/11, faced with this reality. The number one oil exported in the world, Saudi Arabia, has a violent and growing Islamic militancy movement. Osama and 15 of the 19 hijackers on 9/11 are from Saudi Arabia. An 'unholy' status quo has existed between the Royal Saudi Family and Wahabi Islam for generations. There was (and is) the very real posibility that the Royal Family may one day go the way of the Shah of Iran. If that happens we would have both the 1st and 2nd largest known sources of oil potentially cut off from us. Our National Security, Economy and consumer driven way of life would not - could not permit that.
Point 2:
What is Osam'a biggest Beef with the US - in fact it was the driving principle behind the formation of Al Queda in the early-Mid 1990's?
?
The fact that we have a military presence on the Holiest land in Islam. We are Infidels in their eyes because of that, something few Americans can comprehend but it is very fundemental to their Religion - and hatred for us. And they view us as there to prop up a corrupt Saudi Regime that doesn't give a damn about using the vast wealth of Saudi Arabia for its people - just themselves.
Of course our real reason was for our military presence at Prince Sultan Air Base was the UN santioned No-Fly Zones.
Hence - A Very Real strategic consideration of the Bush Administration was:
1) If Iraq is toppled we don't have to worry about the No-Fly Zones and we can withdraw from Saudi Arabia, something already underway.
2) Under a friendly government, Iraq would serve as a 'Fail Safe' source of oil should Saudi Arabia's Royal Family fall.
And they thought - "And who could argue against getting rid of a bastard like Sadaam anyway"
?
There is one other consideration the Neo-Cons talked about yet you here so little about these days. That is the connection to our ally Israel and their interests.
Remember the talk from the Right (Weekly Standard particularly) of "The road to Jerusalam goes through Bagdad?" Well because Sadaam did fund Palestinian suicide bombers and Israel was concerned if sanctions were lifted on Iraq, they may one day have to bomb a reconstituted Iraqi nuclear capacity as they did back in 1982. With Isreal locked (at the time) in a new Infatada, they wanted at least one of the sources of the financial support (Sadaam) to be taken out.
The problem with ALL these assumptions of course is they underestimated the potential for an Iraqi resistance, the reaction of the Arab world in general, and they completely failed to take into account Iraqi history.
The Turks from the days of the Ottoman Empire could not 'control' this area and largely left it alone to be ruled by the locals, nor could the British in the 1920's. Iraq's Suni', Shiha, and Kurd populations are a "Fake" nation..... clumped together by the British and called 'Iraq' after the Ottoman Empire fell in 1919. Iraq's disparate groups has since been held together largely by dictatorial rule. But it kept the separate factions from fighting.
Now it is our job to keep it together, yet I fear we have only created the conditions for Civil War in that country.