The terrorist attacks on the twin trade towers and the Pentagon kindled an immediate, renewed focus on homeland defense. Since then, efforts to combat physical terrorist threats have rightly taken center stage. However, the need to protect our national information infrastructure (NII) from an increasing array of cyber threats is equally urgent. This paper will argue that characteristics of the NII drive DoD to a more active role in its defense. It will then discuss NII protection efforts to date, shortfalls in those efforts, and Canada's emerging NII protection structure as a potential model for the US to adopt. Finally it will argue that DoD should have an expanded and better-defined role in NII defense - not as a playground bully that dominates everything, but as a full-fledged team player in areas where it can best apply its expertise.