These are executive decisions. The buck stops at the White House. in 1991, the right thing to do was to stop the killing, if the decision was to leave Saddam in power. What truly screwed things up was Bush giving the Shiites cause to believe that the US would intervene on their side, thereby resulting in a revolt that was crushed with great slaughter by Saddam. That was probably a factor in Shiite distrust and resentment of the US occupation during the Operation Enduring Freedom, a sentiment that manifested itself in the decision to evict US troops.
I'm not blaming Franks for not slaughtering Saddam's army in 2003 - I'm blaming Bush. Again, how many of the enemy to kill is ultimately an executive decision, because of the foreign relations and international law aspects of the decision.
After 9/11, the right thing to do was to ask Congress for 20 additional army divisions, in preparation for occupation duty and future military operations. Instead, he did a tax cut and asked people to go shopping.
I thought then that this administration was either awfully confident or awfully wrong about the outcome of future military operations. I had expected, at minimum, an expansion of ground forces or even a limited draft for occupation duty. Political capital has a limited shelf life. If you don't seize the moment, that moment is lost forever.
We garrisoned postwar Japan with 350K troops for 5 years. This was a country that lost 4% of its population including perhaps 1/3 of its 18-28 fighting age men. It was also a country that had been near starvation for years, and had suffered 500K civilian deaths through firebombings and nuclear strikes. And Japan is an island nation, whose waters were extensively patrolled by the US Navy, apart from which no neighbor (all of which had suffered from Japanese attacks) was likely to want to help the Japanese fight the US. On top of it all, Japan's God Emperor, Hirohito had, in exchange for immunity from prosecution, told his people to surrender and stop fighting. As a living god, the odds were good that his orders would be followed.
Nonetheless, 350K occupation troops were allocated for a beaten nation that would have seen millions of famine deaths if not for the end of the war. And Bush thought 140K occupation troops would be enough for Iraq, whose fighting age Sunni Arab troop numbers had barely been grazed.
You might say this is Monday morning quarterbacking. My response? I'm just a keyboard jockey doing this analysis for fun. If I were the decisionmaker, on the basis of my resources and my time (a few hours a week), I'd cut myself some slack.
Bush had an army of millions in the Federal bureaucracy working for him, and thousands of analysts whose job was ultimately to answer any questions he cared to ask. All he had to do was formulate those questions, or appoint people to do it for him. He had no excuse for dropping the ball. If we had 350K troops in Iraq (or Afghanistan), we would have suffered fewer combat deaths. Instead, Rumsfeld went with the nutty notion that penny packet deployments necessitated by a small occupation force would lead to fewer casualties (his "more troops = more casualties" assertion).
My view is that Bush, Rumsfeld and Cheney had too much business experience. They ran the war like an established profitable business, trying to squeeze out efficiencies. Except the ultimate success of the enterprise was in doubt from the beginning, not because the US lacked resources, but because it lacked the popular support to lose thousands of men for complete strangers in a country with an alien, hostile and, frankly, barbaric culture. The time to ask for the manpower and money necessary for victory was right after 9/11. Bush dropped the ball then, and then divided up the limited US forces available for an invasion of Iraq. This is the definition of incompetence. Instead of overkill (500K troops for 5 years or so), they placed 140K troops there and suffered 4K dead at the end of Bush's 2nd term, thereby paving the way for an Obama victory in 2008.
Oops!
I was defending the honor of Frederick Franks, who led 7th Corps in the Gulf War. He was often criticized for not killing enough of the Republican Guard during the Gulf War, under Bush the First. I mistook Tommy Franks for him - a whole other General Franks. Fred Franks kicked ass!
I’m also just a keyboard jockey doing this analysis for fun, but I give Bush a lot of credit for biting off a difficult and dangerous task, and have been impressed by his character in respecting and caring for those who served. As Teddy Roosevelt was fond of saying, credit belongs to man in the arena.
In 2003, we were heroes to many Shia in Iraq, after removing the brutal persecutor Saddam - a Hitler-like monster. Even Iran, as “Death to America” happy as they were, took some time before starting to agitate against the US within the Iraqi Shia population, so powerful was the popular joy over the downfall of Saddam. In 2004, American soldiers could walk around Baghdad individually.
But Iran was immediately at work infiltrating their loyalists into positions of power in the new Government, and preparing to fight in Iraq. Iran had much more to fear from the US than Syria - suddenly surrounded in Afghanistan and Iraq by their “Great Satan” who had openly called them part of the “Axis of Evil” (which they were). The Iranian/Saudi surrogate war entered a new phase when Saddam fell, with the Gulf Arabs still funding their B team terrorists, while Iran stood up its militias within the Shi’ite community.
I believe that dissolving the Iraqi Army was absolutely necessary, because they were totally an organ of the Ba’ath Party (which had twice conquered Iraq through Secret coups). The Ba’ath had extensive plans to retake power. The Army was central to their plans, and was by far the most powerful asset they could use to do it. US occupation forces would have been vulnerable to sudden mass slaughter, if the Iraqi Army had launched a sudden surprise revolt targeting the Americans.
So Iraq was a big undertaking, and Democrats (as well as many Republicans) were actively seeking to limit resources, so Rumsfeld was was selling his better/faster/cheaper concepts to accomplish the mission within the financial constraints from Congress. The bottom line was that no 20 new divisions would be coming from Congress. Of course, we could have done more with more, and at less risk. We had a budget then, and great difficulty in raising spending without raising taxes - it is shockingly different from today’s environment of wanton disregard for math.
From my perspective, Rumsfeld was the big proponent of the lean footprint, and the State Department institutionally desired (as is typical) less military influence or control of the situation. Ultimately, I believe you are right, that a lot more resources would have decisively improved the situation. Congress then exercised the power of the purse.
The conventional approach to reducing the size (and thereby the cost and casualties) of your occupation force, is to install a strongman regime, and let them impose order. We tried to both have a lean occupation force (based on theories that technology and tactics could be force multipliers), and to allow a lot of political freedom. Enemies exploited freedom to organize, and there was a dearth of honest leaders to administer the Government. A more Machiavellian use of the CIA and an imposed Iraqi strongman regime could have made a big difference as well, but with other costs.
As you noted, the Mongols were incredibly efficient in occupation. They did in fact use repeated instances of wholesale genocidal slaughter to enforce their rule. Parts of Afghanistan, like Bamiyan Province, were totally depopulated by the Mongols in retribution for rebellion. To this day, the local Hazara population are descended from the Mongol occupation force.