The basic U.S. strategy in Iraq was, historically, sound. You help the locals get organized so they can take care of themselves. That means elections and help to rebuild local institutions. But there's never a guarantee that will work. The U.S. Marines were in Haiti for nearly 30 years (from 1914), and the country still reverted to dictatorship and poverty when the marines left. This exposes a truth that many refuse to acknowledge. Fixing countries isn't easy. The "civil society" that we in the West take for granted, cannot just be conjured up. The harmonious relationships that enable some democracies to work, are not a given. Those relationships often require a lot of bad habits to be changed. This is not easy. Just check a history book.
Further, the Sunni Arabs were too few to seize power in Iraq. All the Sunni Arabs could do is wreck Iraq, which they nearly did until we responded with the surge offensive.
Further, the fight must go on to fight corruption in Iraq and build rule of law even after our troops aren't being shot at on a daily basis:
Iraq can either be a turning point in Middle Eastern history, or the democracy can be corrupted, as it was in 1958 when the constitutional monarchy was overthrown by the Sunni Arab dominated military. To that end, the Iraqis are trying to negotiate a long term treaty with the United States that would include an American promise to "coup-proof" elected Iraqi governments. That's novel, but depends on the election process remaining uncorrupted. Nothing is simple in the Middle East.
We invaded Iraq for good reasons, and the chance to end the cycle of jihadis responding to despotic Arab regimes by attacking the West had to be ended once bugs, gas, nukes, and radiological weapons replaced scimitars and made mega-deaths at the hands of these nutjobs possilbe. If we fail in this, we will have simply achieved an old-fashioned victory of putting our SOB in the palace rather than an enemy. This is what foreign policy "realists" have wanted all along. But this will simply be a temporary victory under the old template that only plays whack-a-mole with the threats. And Iraq, like Egypt and Saudi Arabia, might become a "friendly" Arab state that nurtures jihadi grievances and jihadi recruits.
We are winning the Iraq War on the battlefield. We need to win the long-term battle for a free, prosperous, and democratic Iraq to start the process of providing an alternative to despotism or jihadi rule in the Arab Moslem world.
I will quibble with only one point. We did not conquer Saddam's regime with just three divisions. Commonly, it is said we hit Iraq with 3rd Infantry Division, 101st Airborne Division, and a Marine Expeditionary Force (normally with a division-sized ground element). This ignores the British division. It also ignores the fact that we had 60 line battalions (a little over half were Marines) in our three divisions on the eve of war. This is the equivalent of line elements of 6 divisions (ten per division).
Since we used air power to substitute for artillery and didn't build up iron mountains of supplies prior to invading, we could deploy the frontline elements of six divisions without the usual support units for the same number of divisions. So we effectively hit Iraq with 7 divisions. This is well in line with our older policy of assuming a major theater war using 5 Army divisions and 1 or 2 Marine Expeditionary Forces.
Even aside from our fight against al Qaeda in Iraq, fought because al Qaeda invaded Iraq and became just another group of jihadis that the Baathists thought they could use to control Iraq, the Iraq War is truly part of the Long War on terror. A free Iraq could be the wedge that gives the Middle East an oppportunity to break their self-destructive past and defang the appeal of jihadi ideology as a source of solutions to their many woes. Don't dismiss the ability of Arabs to embrace democracy. Asians, Latin Americans, and East Europeans were all said to be too crippled by their histories to become democracies. Let's not forget Japan, Italy, and Germany, either, whose militarist and dictatorial pasts seemed unlikely ground in 1945 for democracy to take root. Just remember that democracy doesn't have to start with caucuses in Iowa to be authentic. Real democracies have different forms of democracy.
Realists would have written them all off and insisted on our thugs being put in power. It wouldn't be realistic to now argue that those countries are unsuited for democracy. One day, if we are successful in our broader struggle, the Iraq War will simply become the Iraq Campaign of the Long War. Like I've said, George the Liberator.
We may be proud of what our troops have achieved in Iraq in the name of America. We can build much more on this foundation if we maintain our resolve.