Well, if you actually listen to the words of the Al-Queda leadership and folks of that ilk, if the US government wasn't so divided, then they wouldn't be fighting like this in Iraq.
That argument always gives me pause. I definitely believed it when it came to interpreting the Vietnam war. If they believe we'll stay there until the last man is dead, would they give up and go home? That's basically the question.
The argument is less and less persuasive to me as I survey the guerrilla wars of the past three centuries, and especially the early 21st, where "asymmetric warfare" is all the rage. The fact is that people who've looked into the subject, referring here to the guerrilla leaders themselves, know that a guerrilla resistance which is popular with the people has overwhelming odds in its favor.
Because of their popularity, the people will generally refrain from turning them in to the opposing military. Instead the locals will usually hide them. And because the insurgents are locals themselves, they can blend into the population: the same guy planting an IED in the wee hours, can pass through the checkpoint with a wave and a nod on the way to his day job. Worse, again because they're locals, the job is never done: you can pacify a city, only to have everything flare up again later. Some of the insurgents flee and return after pacification; some of them simply stay there and keep their noses clean for a while.
Knowing these things, the military faces a hideous challenge: how do they protect the "friendlies" from the "enemy," when the friendlies and the enemy are impossible to tell apart? If you catch them in the act, the you know they're the enemy--but most of the time, you have no idea which is which. This puts the soldiers under a terrible strain, because despite their best intentions to work with the friendlies, to win "hearts and minds," and all the rest, they know that the kids they're playing soccer with, or the ladies they help across the street, might be the same ones that planted the bomb that killed their buddies. Everyone is suspect. That's an intolerable strain, and as time goes by it's impossible to endure that strain without increasingly seeing every "friendly" as a probable enemy in disguise.
As that strain increases, accidental killings of "friendlies" will also increase. A few who tend to be mentally unstable will take to raping and pillaging, like the head case who was recently convicted of raping a girl and killing her family. But the decent majority will have more accidents too, simply because they're on a continuous hair-trigger alert in an environment in which everyone is a potential enemy.
The killing of friendlies will always increase the ranks of the insurgents, as well as popular support for them. Relatives and loved ones will want revenge. That's especially true in the case of Arab culture, where the concept of revenge dates back to the earliest bedouin, but it's true of people everywhere.
Knowing that the odds overwhelmingly favor the insurgents, and that every effort to quell the insurgents actually helps their cause, makes guerrilla insurgency a very attractive strategy. It has been used successfully many times, whether or not the occupying force was lacking in political support back home.
So the likeliest analysis indicates that the insurgency was the strategy of choice on its own merits, and internal debate concerning US foreign policy is not to blame for it.
--Len.