WASHINGTON — Quite a “defining moment” in Iraq, wasn’t it? At this rate, John McCain is going to be proved right: The war will last a century.

That is indeed what McCain said, by the way, no matter how his apologists try to spin it. Those who claim that by “a hundred years” McCain was talking about a long-term peacetime deployment like the U.S. military presence in South Korea are being disingenuous or obtuse. In and around Seoul, citizens aren’t shooting at American soldiers or trying to blow them up with roadside bombs — and U.S. combat forces aren’t taking sides in bloody internecine battles over power and wealth.

It was George W. Bush who called last week’s fighting in Basra and other Iraqi cities a defining moment for the fledgling government. By that standard, Prime Minister Nouri al-Maliki has been defined as an impulsive leader and an inept general — and his government as a work barely in progress.

Maliki’s decision to send troops into Basra and root out the “criminal gangs” that controlled the city was praised by the White House as a bold move to assert the Iraqi government’s sovereignty. In reality, though, it looked more like an attempt to boost Maliki’s political standing by dealing a blow to the Mahdi Army — the biggest and most powerful Shiite militia — and its leader, the cleric Moqtada al-Sadr.

Iraqi forces launched their offensive and were immediately met by what Maliki’s defense minister called unexpectedly strong resistance. In other words, they ran into a buzz saw. Maliki went to Basra to personally oversee military operations. History will not confuse him with Napoleon.

The government might have suffered a humiliating defeat if not for the face-saving intervention of U.S. and British air power, and a bit of British artillery as well. At least the United States didn’t have to go it alone. It was the British military, after all, that had declared its job done in Basra and withdrawn, knowing full well that the city was controlled by gangs and militias, not the central government in Baghdad.

Meanwhile, Maliki’s putsch had inflamed Shiite communities throughout the country, including the vast Sadr City neighborhood in Baghdad. The tranquillity brought about by Bush’s ballyhooed “surge” turned out to be as evanescent as a rainbow.

Maliki was forced to sue for peace, Sadr magnanimously accepted, and the fighting ebbed. The Mahdi Army remains entrenched, in Basra and other cities, and armed to the teeth. Maliki’s regime looks less like a government than just another faction — albeit one with a couple of big brothers who will come in to finish any rashly started schoolyard fights.

All of which illustrates the insanity of the open-ended Iraq war policy that Bush has followed and that McCain vows to perpetuate.

What, exactly, did the United States use its military might to accomplish last week? We intervened in a struggle among various Shiite power centers for control of a city where much of Iraq’s oil industry — and thus much of its potential wealth — is based. We supported a political figure who was trying to weaken another political figure in advance of upcoming elections. We boosted the morale and fervor of the most implacable opponents of continued American occupation.

Does any of this have anything to do with our nation’s vital interests? I suppose you could argue that Basra is important because of the oil, but the city is no more under Baghdad’s control today than it was two weeks ago.

Please note that throughout this episode, you haven’t heard the name al-Qaida. According to Bush and McCain, isn’t Iraq supposed to be the central front in the war on terrorism? Wouldn’t the only plausible reason for continuing the occupation of Iraq be to fight terrorists — rather than help one Shiite leader against another? And what’s the strategic reason for backing Maliki, who recently gave Iranian leader Mahmoud Ahmadinejad a red-carpet welcome to Baghdad, over Sadr, who is believed to be living in Iran, enjoying Ahmadinejad’s hospitality?

Bush’s troop surge, remember, was supposed to buy time for two things to happen: Iraq’s political leaders were to achieve reconciliation, and Iraq’s armed forces were to improve to the point where they could conduct operations on their own. On both counts, we see the results.

If Democrats are going to take several more months settling on a presidential nominee, they had better find some way to stop giving John McCain a free ride on Iraq. He should have to explain why he wants to keep us on George Bush’s long, winding path to nowhere.

Eugene Robinson’s e-mail address is eugenerobinson(at)washpost.com.