True, the war is not over. As Gen. David Petraeus repeatedly insists, our (belated) successes in Iraq are still fragile. There has already been an uptick in terror bombings, which will undoubtedly continue as what's left of al-Qaeda, the Sadrist militias and the Iranian-controlled "special groups" try to disrupt January's provincial elections.

The more long-term danger is that Iraq's reborn central government becomes too strong and, by military or parliamentary coup, the current democratic arrangements are dismantled by a renewed dictatorship that abrogates the alliance with the United States.

Such disasters are possible. But if our drawdown is conducted with the same acumen as was the surge, not probable. A self-sustaining, democratic and pro-American Iraq is within our reach. It would have two hugely important effects in the region.

First, it would constitute a major defeat for Tehran, the putative winner of the Iraq War according to the smart set. Iran's client, Moqtada al-Sadr, still hiding in Iran, was visibly marginalized in parliament -- after being militarily humiliated in Basra and Baghdad by the new Iraqi security forces. Moreover, the major religious Shiite parties were the ones who negotiated, promoted and assured passage of the strategic alliance with the U.S., against the most determined Iranian opposition.

Second is the regional effect of the new political entity on display in Baghdad -- a flawed yet functioning democratic polity with unprecedented free speech, free elections and freely competing parliamentary factions. For this to happen in the most important Arab country besides Egypt can, over time (over generational time, the timescale of the war on terror), alter the evolution of Arab society. It constitutes our best hope for the kind of fundamental political-cultural change in the Arab sphere that alone will bring about the defeat of Islamic extremism. After all, newly sovereign Iraq is today more engaged in the fight against Arab radicalism than any country on earth, save the United States -- with which, mirabile dictu, it has now thrown in its lot.