A battery operated cable security seal for cargo containers and the like includes a housing with a transparent cover for visual inspection of illuminated internal green or red LEDs, the red LED representing a tampered state of a stranded metal locking cable, which has a length sufficient to secure the keeper bars and hasp of a cargo container door. The cable has an internal conductor whose conductivity, e.g., resistance, manifests a tampered condition when severed and also if reattached, e.g., by a solder or spliced joint and so on. The electrical continuity of the conductor is monitored by a circuit in one embodiment for a severed state, i.e., tampering, and whose resistance is monitored in a second embodiment correlated optionally to either or both ambient temperature and a battery output voltage. The seal housing has two compartments one being hermetically sealed and contains the circuitry and the other containing a cable locking device for receiving and locking the cable to the seal. The circuit includes an RFID tag which may be part of a mesh network configuration with other tags.