The listening post/observation post is a method employed by infantry units in combat to increase battlefield situational awareness and prevent surprise by the enemy. This technique is costly to the employing unit in terms of manpower requirements and increased risk to friendly personnel. To reduce these costs, we created a prototype, the Mobile Situational Awareness Tool, that combined commercial off-the-shelf components with wireless unattended ground sensors for the purpose of automating the listening post/observation post for the tactical infantry unit. The prototype system incorporated wireless sensor node prototypes created by the Defense Advanced Research Projects Agency, originally intended for the creation of a smart minefield. A web application was created using a custom Node.js server that enabled cross-platform monitoring of the system by warfighters in the field with mobile smart-devices to include smart-phones and tablets. Field-testing of the prototype showed the system capable of detecting and classifying intruders in the sensor field but revealed that more robust threat classification algorithms utilizing multiple sensor modalities would yield a greater degree of automation and autonomy.