Guerrillas number over 20,000
Some honest US officials in Iraq are finally admitting that US forces are not meeting a vanguard of international terrorism there but rather some 20,000 angry Baathists who fear for the fate of Sunni Arabs in the new regime.
This way of putting the problem suffers from conceptual problems, too. The number of guerrillas is not stable. It can grow or shrink easily. When the US besieged Fallujah, it turned virtually all able-bodied male tribesmen into guerrillas (I’d say that would come to 50,000 right there). The sheer size of the defending force in Fallujah is among the few rational explanations for the failure of the US Marines there (the disastrous political fallout of the siege was more decisive, probably). Once the siege ended, a lot of the defenders put down their weapons, though significant cells continued to be active in plotting car bombings and other acts of resistance from the city.
Likewise, when the US attempted to arrest Muqtada al-Sadr, it enraged the ghetto Shiite youth, many of whom took up arms against the US forces for the first time. When the US backed down and left Muqtada alone, thousands of Shiites stood down. (East Baghdad is relatively quiet now, and the US patrols can even pass through again).
As the article notes, many guerrilla leaders could potentially be coopted by a new Iraqi government. If there are elections in January, it seems likely that they (or their cousins) will gain seats in parliament.
So, anyway, I just cannot understand why the US military continues to think in such a static and unimaginative way about the resistance. In a country with so many armed clans and urban youth gangs, it cannot so easily be nailed down. But it certainly is very large, and at some points significantly larger than 25,000.