|Sometimes y'just gotta turn Mother's picture|
to the wall
There is a reason why starting wars is usually frowned upon, and is historically an ultimately unprofitable undertaking. America is rightly proud of her earlier commitment to ending wars rather than starting them. As children, we were taught that events like the German invasion of Poland, the attack on Pearl Harbor and the North Korean invasion of the South were not just wrong, but acts of comprehensive evil that led to utter destruction and ruin. Invading a nation with whom your nation is not at war is by definition a desperate bet-the-farm move, because you will have to use such overwhelming force and such brutal tactics to control the population, the borders and prevent other nations from working together to roll back your aggression that the days where such an undertaking could actually have a definitive outcome are long past.
If there is any single overarching lesson to be learned from the hubris and horror of the American experience, it may be that the world is a very complicated place, and he who over-simplifies a problem and therefore doesn't think hard enough about his response is guaranteed to fail. There is more than one kind of war. There is more than one kind of peace. There is more than one kind of revolution. There is more than one kind of democracy. There is more than one kind of dictator. The invasion was morally and ethically wrong, and what's worse, it was utterly unnecessary. But the people who ordered it were right about something - there was never any doubt that the US military could quickly defeat the Iraqi armed forces, go to Capitol and depose the Baath government. The blunders that followed were all based on calculations of what the US should do next.
Had the forces imposed a 90 day limit on their time in - country, overseen the creation of a transitional government, maintained the Army and police forces and sought to get Iraqi civil society up and running as quickly and painlessly as possible, we might have seen a different history. Certainly there was going to be Sectarian violence - the minority Sunnis had brutally dominated and oppressed the Kurds and Shi'a for decades, and after they lost their absolute grip on power, blood was going to spill. But without the occupation by foreign troops to focus the hatred and violence, perhaps cooler heads and some kind of rational process might have prevailed.
Ultimately, it doesn't matter, because attacking Iraq was a horrific crime in the first place, and to think anything good might come from something like that leaves the world in a very precarious position. It is necessary to understand that in the 21st century, there is nothing to be gained by any nation from warfare. Military force must be reserved for defense - of nations, of civilians, of humanity. In a time in the near future when wars will be fought over things as basic as food and water, there is going to be a whole new set of rules. We'd be well served to start thinking about them now.