Cliff May offers a bit of clear analysis of evidence in Iraq:

I also would argue that the evidence does not suggest that most Iraqis prefer not to be free, that most would rather not choose their leaders, that a majority enjoys a good suicide bombing every day or two.
The evidence suggests that a fanatical, determined minority can do vast amounts of damage, can destroy faster than anyone can build, can so terrorize people that they relinquish their hopes in exchange for protection. Why is this surprising? When the Bolsheviks took over Russia, it was not because most Russians were Marxist-Leninists. Most Germans were not Nazis in the early 1930s. When New Jersey store owners pay the Mafia protection money it’s not because that’s the way they like it.

May then quotes some more-action-oriented analysis by Fred Kagan:

The lessons of the U.S. military program in Iraq are reasonably clear by now. American forces, working with Iraqis, can clear areas dominated by terrorists and insurgents. The efforts to do so lead initially to an upsurge in violence as the insurgents resist, but then to greater calm. In places like Tal Afar, Al Qaim, and other small towns along the Upper Euphrates River valley, Sadr City in 2004, and even Falluja (in the second battle in 2004), clearing operations have succeeded. In many of these cases, however, the U.S. command left inadequate American forces behind to help the Iraqi troops hold the area, with the result that insurgents gradually infiltrated and began to destabilize these regions once again. The lack of any coherent plan to move from one cleared area to another, moreover, often meant that stabilized towns were islands in a tumultuous sea.
The failure to hold cleared areas results in part from inadequate U.S. troop levels, but primarily from a strategy mistakenly obsessed with the irritation the American presence causes.

Identification of that key obsession points to the root problem, which is located squarely within American society itself. One shudders to think that undermining the United States’ project of making the world more secure and peaceful by transforming the Middle East is a deliberate strategy of a large (and elite) cohort on our own shores. If so, then that cohort is utterly blind to the domestic consequences of doing so — perhaps even to the notion that there could possibly be consequences.
At the very least — in the charitable interpretation — the obsession with conducting the Perfect War, with anything less negating the possibility that legitimate war can exist, grows from a fantasy that we can treat current events as we treat history: with analytical aloofness and an inclination to reinterpret according to ideology. Even among erstwhile supports of the war in Iraq, one hears such constructions as “we now know that the war was a mistake.” But such statements are nearly devoid of actual sense.
To be fair, Jonah Goldberg follows his version of my paraphrased quotation by stating that “Congress… was right to vote for the war given what was known — or what was believed to have been known — in 2003.” But the clarification invalidates the lead. Unless we are speaking within the context of history, we cannot identify choices as mistakes based on that which could not have been taken into consideration. (Note the etymology: mis-take.)
With history, we’ve broader perspective of what was misunderstood or simply not known. In contemporary terms, we can only guess at what is not known, and our individual guesses are our individual ideologies. In the present, disclaiming mistakes based on unknowns implies mistakes in values, and in the context of current action, we should seek to identify errors not for judgment, but for improvement.
The urge to judge each other by criteria of what will be known in the future relies on ideological division and disallows cooperative handling of shared circumstances. Those who, on ideological grounds, “opposed the war before it was popular to do so” (as one local congressman is currently stating in radio ads) aren’t claiming mystical foresight, but rather that their ideology is more true. Such thinking reduces cooperation to subjugation of one side to the other.
We can (or ought to be able to) read history and identify our predecessors’ mistakes without feeling either superiority or shame because we understand that historical analysis does not (or should not) involve value judgments: we analyze subjects and their circumstances, so we can conclude “this turned out to be a mistake.” With current affairs, we cannot remain so aloof. This is not an admonition, but a statement of fact: it cannot be done. We will root for a side; if we are not rooting against a shared enemy, we will necessarily be rooting against some faction or other among our ostensible allies, and speaking of mistakes implies inferiority.
This division in the United States is part of what has motivated the insurgents in Iraq. They don’t have to defeat the sleeping giant. They merely have to defeat neocons or conservatives or Republicans, all of whom have broader interests than nationalism and are therefore vulnerable to leverage on any given issue and may cave on the war in order to protect their core objectives, whether ideological or political.
Apart from insisting that we conduct our debate about the War on Terror in terms of strategy, rather than recrimination and political gamesmanship, I’m not sure what we can actually do to overcome this fatal chink in our national armor, this weakness of character. At the risk of reducing global matters to local politics, I’ll state that I’m quite sure that rewarding the likes of Linc Chafee for straddling the line between his party affiliation and his own ideological prescience, so to speak, is not the way to do it. On the other hand, I’m intrigued by the possibility that swerving the car toward the precipice through a Sheldon Whitehouse vote might scuttle the wrong-headed fantasies and unhealthy obsessions that are leading us toward a calamitous future.