This paper examines the systems engineering process of the development of a new lightweight weapon system, a Short Range Anti-tank Weapon (SRAW) for the United States Marine Corps. The systems engineering approach has been applied to this system. The need for such an anti-tank system is established from examining currently fielded anti-tank systems. The maintenance concept, operational requirements, functional analysis, and requirements allocation are presented with an emphasis on the human interface. The SRAW optical sight requirements are presented to illustrate the flow-down of the systems engineering process to the component subassembly level. The results of a field test verification of the optical sight requirements are presented as one example of the iterative system development process.