Garry Trudeau interview @ RollingStone.com

Key quote:
RollingStone.com: "Do you see parallels between Iraq and Vietnam?
Both were discretionary wars entered into under false assumptions, and you could argue that both initially had worthy goals. The Iraq adventure, however, was crippled by a fatal arrogance from the onset. The Powell doctrine of using overwhelming force to reach achievable goals with a clear exit strategy -- conceived in reaction to mistakes made in Vietnam -- was summarily discarded, inviting nearly all the consequences the doctrine was designed to avoid."