-- During the Anbar Awakening, from 50,000 to 100,000 foot soldiers not only left the enemy, but also joined our side, contributing knowledge of the insurgency's inner workings.

-- Iraqi Prime Minister Nouri al-Maliki, elected with support from Shiite extremists, went south to take on Iranian-backed militias in Basra -- establishing himself as a national, not just Shiite, leader.

-- And Iraq's Sunnis fully joined the political process, which now absorbs much of the energy that might otherwise spill into the streets.

None of these achievements is perfect or permanent. But foreign policy success is judged by comparative, not absolute, standards. The comparison here is to an American withdrawal two years ago -- which would have been Vietnam II, and worse. AQI would have controlled whole regions of Iraq -- it had already established a provisional government in Anbar -- gaining a base of operations against friends in the Middle East, against allies in Europe and against the United States. With Iran's help, Iraq's Shiites would have fought a bloody civil war against al-Qaeda. Sunni neighbors would have been tempted to intervene, leading to a regional war played out on Iraqi soil. Iraqi citizens might have been subjected to genocidal violence. And America would have failed -- not on a distant Asian battlefield like Vietnam -- but in the Middle East, a center of our global interests since World War II.

So what has been accomplished by all the sacrifice, patience and resources that Iraq has consumed? If Iraq succeeds -- if it can bear the weight of its own sovereignty -- it will be a historic advance. Jeffersonian democracy was never assumed or promised. But an Iraqi accommodation in which Shiites, Sunnis and Kurds find common purposes through democratic processes would be an example to the region, which is seeking new models of progress. And the development of a stable American ally in the Middle East that fights terrorism would be a tremendous geopolitical achievement. In spite of past debates, Obama should view this prospect not as a chore, but as an opportunity.

Even if Iraq falls back to the level of political mediocrity that surrounds it, the situation has changed from two years ago. If America had retreated then, it would have been a failure of our will and a failure of our military. But we did not fail. Our military adapted. Our leaders and country persevered. We have given the Iraqis what we owed them -- a decent chance at success, the only gift a liberator can give. Now, a failure would be sad and challenging -- but it would be their own.