So what the minimum threshold for victory?
NYT (requires registration)
Profusion of Rebel Groups Helps Them Survive in Iraq
Here is a small sampling of the insurgent groups that have claimed responsibility for attacks on Americans and Iraqis in the last few months…
…But whatever the appearances, American and Iraqi officials agree on the essential structure of the Iraqi insurgency: it is horizontal as opposed to hierarchical, and ad hoc as opposed to unified. They say this central characteristic, similar to that of terrorist organizations in Europe and Asia, is what is making the Iraqi insurgency so difficult to destroy. Attack any single part of it, and the rest carries on largely untouched. It cannot be decapitated, because the insurgency, for the most part, has no head. Only recently, American and Iraqi experts say, have they begun to grasp the new organizational structure that, among other things, is making the insurgency so difficult to stop.
“There is no center of gravity, no leadership, no hierarchy; they are more a constellation than an organization,” said Bruce Hoffman, a terrorism expert at the Rand Corporation. “They have adopted a structure that assures their longevity.”
The insurgency’s survivability presents perhaps the most difficult long-term challenge for the Iraqi government and American commanders. The primary military goal of groups like Al Qaeda and Ansar al Sunna is not to win but simply not to lose; to hang on until the United States runs out of will and departs. Even killing or capturing the leader of Al Qaeda in Mesopotamia, Abu Musab al-Zarqawi, many Iraqi and American officials say, will not end the rebellion.
In a war as murky as the one in Iraq, details about the workings of the insurgency are fleeting and few. But what is available suggests that the movement is often atomized and fragmented, but no less lethal for being so.