Successive U.S. administrations that sucked us into Vietnam may have been colossally wrongheaded, but at least their explanation for doing so was clear and consistent: We must prevent the communist dominoes from falling. Increasingly Americans disagreed with the explanation, nonetheless it was what it was, and at least comprehensible.

Yet, although our intervention in Iraq was of equal if not greater wrongheadedness, the explanations for launching it, and then staying the course, remain a matter of national bewilderment. I can think of no other U.S. intervention that amounted to what seemed like a whim, nor one whose official rationale ever changed so vigorously over time.

First, and at first in toto, there were of course those ghastly weapons of mass destruction that required our attention, for their owner -- whose middle name seemed to be "9/11" -- posed an imminent threat. When those proved elusive, a thorough "regime change" became the sole explanation of our casus belli. But soon, after making short work of that objective, the better angels of our humanitarianism were called upon; that, we were told, was why we were there -- to save Iraqi lives, as we whacked them by the thousands.

Also came, in time, the stirring explanation of the need to spread democracy, which lasted until this administration realized that Iraqis' democratic beau ideal was more Bill Tweed than Tom Jefferson. Tossed into this mix, from time to time, were also the explanations of some needed Middle East map redrawing, the bold defense of the U.N.'s integrity, and the occasional and murky reference to guarding against the wicked designs of Iraq's neighbors.

If I failed to properly order the chronology of that explanatory mess, not to worry. It isn't important, because the official explanations were utter bullshit to begin with, as evidenced by their pick-and-choose metamorphoses. They were only tossed out for public consumption in answer to the sporadically posed query: Say, what is it, again, that we're doing over there? Some administration official would then say something that sounded good and we'd all be content for a while; until, once again, we saw the explanation made no sense. So we asked for another, and promptly got another. 

Now, five years later, we still have no honest idea of why we went, but at least the forthcoming explanations for staying are down to one: We're there because we shouldn't leave. At least it has a certain simplicity. And slowly, if opinion polls are to be believed, we seem to be buying it, just like we did for years on end with those theoretical dominoes. 

Our gradual acceptance isn't that surprising, really, given that the war is less and less a living room affair. There are plenty of other shiny new news stories to keep us amused, and what noteworthy death and destruction does take place over there is sold as a sure sign of improvement. All that getting shot at just shows we have "them" on the run, whoever they are, so we can't leave now. And the flip side? Once "they're" pacified, we can of course stay even longer. But before we stay longer, we must stay long enough.

The same Catch-22 logic is deployed in defense of how many "we," vs. "they," are there. "We have every desire to continue with the withdrawal of forces" this summer, said one military official this week [1]. However, and this is a good one, "although ... U.S. troop strength at that point should be about where it was before a 'surge' in deployments began last spring -- approximately 130,000 -- the military official said the net number remaining may be larger." Hence the number of troops on the ground is inversely proportionate to the number of troops withdrawn.

Yet I trust that's unproblematic for the troops themselves, since their commander in chief -- He of the Original Whim -- told their uniformed contemporaries in Afghanistan that their getting shot at, dodging roadside bombs and picking up the pieces of their buddies is "in some ways romantic." One strains mightily to imagine such wretched stupidity coming out of the mouth of an Abraham Lincoln or Franklin Roosevelt -- or for that matter, even a Lyndon Johnson or Richard Nixon. But one's strain is unproductive. 

Meanwhile, "in congressional testimony next month, [Gen. David Petraeus is] expected to describe continued but slow improvement in military and political conditions," as military conditions, after five years, worsen and political conditions, after five years, remain a stagnated free-for-all.

Petraeus' ambassadorial sidekick, Ryan Crocker, will be joining in the testimonial headfakes, while conceding, as he did in mid-March, that the whole, endless mess is, "like everything else here, still very much under development." After five years.

But if our staying seems bewildering, it holds not a candle to the original mystery. After 4,000 dead Americans and anywhere from 100,000 to 600,000 dead Iraqis, we still don't know why we went there in the first place. And as American wars go, that's a historic first in itself.