Found this in the Wall Street Journal Online
Those who fear another Vietnam in Iraq (as opposed to those who hope for one, who are impervious to reason) should bear in mind that the situations are entirely different. Vietnam was a defensive war in which the enemy had territory of its own and the support of a rival superpower. In Iraq, guerrilla remnants are all that is left of a vanquished foe. The situation is more analogous to postwar Germany, where, as History Today explains, the occupying Allies faced attacks from a guerrilla/terrorist force called the Werewolves, which was not organized until the fall of 1944:
The Werewolves specialised in ambushes and sniping, and took the lives of many Allied and Soviet soldiers and officers--perhaps even that of the first Soviet commandant of Berlin, General N.E. Berzarin, who was rumoured to have been waylaid in Charlottenburg during an incident in June 1945. Buildings housing Allied and Soviet staffs were favourite targets for Werewolf bombings; an explosion in the Bremen police headquarters, also in June 1945, killed five Americans and thirty-nine Germans. Techniques for harassing the occupiers were given widespread publicity through Werewolf leaflets and radio propaganda, and long after May 1945 the sabotage methods promoted by the Werewolves were still being used against the occupying powers.