The Office of Naval Research's Virtual Technologies and Environments (VIRTE) program is developing leading edge technologies for immersing humans in Virtual Environments (VE). This paper will examine some of the challenges in using VE for training specific tasks in the military such as marksmanship and shoot/no shoot decision-making. In particular, we will examine the Marine Corps Indoor Simulated Marksmanship Trainer Enhanced (ISMT), and how the Corps uses it. We will discuss both the technical and human dynamics in the system. We will also examine the current state of VE technologies and the challenges in using them for military training.