WASHINGTON – Barack Obama was a principled opponent of the Iraq War from its beginning. But when he became president in January 2009, he was handed a war that was won. The surge had succeeded. Al-Qaeda in Iraq had been routed, driven to humiliating defeat by an Anbar Awakening of Sunnis fighting side-by-side with the infidel Americans. Even more remarkably, the Shiite militias had been taken down, with American backing, by the forces of Shiite Prime Minister Nouri al-Maliki. They crushed the Sadr militias from Basra to Sadr City.

Al-Qaeda decimated. A Shiite prime minister taking a decisively nationalist line. Iraqi Sunnis ready to integrate into a new national government. U.S. casualties at their lowest ebb in the entire war. Elections approaching. Obama was left with but a single task: Negotiate a new status-of-forces agreement (SOFA) to reinforce these gains and create a strategic partnership with the Arab world’s only democracy.

He blew it. Negotiations, such as they were, finally collapsed last month. There is no agreement, no partnership. As of Dec. 31, the American military presence in Iraq will be liquidated.

And it’s not as if that deadline snuck up on Obama. He had three years to prepare for it. Everyone involved, Iraqi and American, knew that the 2008 SOFA calling for full U.S. withdrawal was meant to be renegotiated. And all major parties but one (the Sadr faction) had an interest in some residual stabilizing U.S. force, like the postwar deployments in Japan, Germany and Korea.

Three years, two abject failures. The first was the administration’s inability, at the height of American post-surge power, to broker a centrist nationalist coalition governed by the major blocs – one predominantly Shiite (Maliki’s), one predominantly Sunni (Ayad Allawi’s), one Kurdish – that among them won a large majority (69 percent) of seats in the 2010 election.

Vice President Joe Biden was given the job. He failed utterly. The government ended up effectively being run by a narrow sectarian coalition where the balance of power is held by the relatively small (12 percent) Iranian-client Sadr faction.

The second failure was the SOFA itself. The military recommended nearly 20,000 troops, considerably fewer than our 28,500 in Korea, 40,000 in Japan and 54,000 in Germany. The president rejected those proposals, choosing instead a level of 3,000 to 5,000 troops.

A deployment so risibly small would have to expend all its energies simply protecting itself – the fate of our tragic, missionless 1982 Lebanon deployment – with no real capability to train the Iraqis, build their U.S.-equipped air force, mediate ethnic disputes (as we have successfully done, for example, between local Arabs and Kurds), operate surveillance and special-ops bases, and establish the kind of close military-to-military relations that undergird our strongest alliances.

The Obama proposal was an unmistakable signal of unseriousness. It became clear that he simply wanted out, leaving any Iraqi foolish enough to maintain a pro-American orientation exposed to Iranian influence, now unopposed and potentially lethal. Message received. Just this past week, Massoud Barzani, leader of the Kurds – for two decades the staunchest of U.S. allies – visited Tehran to bend a knee to both President Mahmoud Ahmadinejad and Ayatollah Ali Khamenei.

It didn’t have to be this way. Our friends did not have to be left out in the cold to seek Iranian protection. Three years and a won war had given Obama the opportunity to establish a lasting strategic alliance with the Arab world’s second most important power.

He failed, though he hardly tried very hard. The excuse is Iraqi refusal to grant legal immunity to U.S. forces. But the Bush administration encountered the same problem, and overcame it. Obama had little desire to. Indeed, he portrays the evacuation as a success, the fulfillment of a campaign promise.

But surely the obligation to defend the security and the interests of the nation supersede personal vindication. Obama opposed the war, but when he became commander in chief the terrible price had already been paid in blood and treasure. His obligation was to make something of that sacrifice, to secure the strategic gains that sacrifice had already achieved.

He did not, failing at precisely what this administration so flatters itself for doing so well: diplomacy. After years of allegedly clumsy brutish force, Obama was to usher in an era of not hard power, not soft power, but smart power.

Which turns out in Iraq to be … no power. Years from now we will be asking not “Who lost Iraq?” – that already is clear – but “Why?”

© 2011, The Washington Post Writers Group