Abstract: A taut wire fence system comprises wire-supporting anchor posts that maintain the taut wires of the system in tension. Sensor posts having tension sensors mounted therein are positioned between pairs of anchor posts to monitor changes in tension caused by intrusion attempts. To protect against attempts to bypass the tension sensors (such as by cutting the taut wires while using a frame device to maintain wire tension), one or more tensioned cable segments are provided in tension between the anchor posts (preferably along the lower portion of the fence) to form an electrical path. An electrical monitoring device is then used to monitor the continuity of the electrical path. The tensioned cable segments are preferably formed from a special cable that includes an outer layer which forms a physical barrier to cutting.