Methods and apparatus are provided for securing and/or tracking cargo containers. The security unit comprises a positioning receiver configured to provide a position of the cargo container and a memory configured to store a first geocentric zone and a second geocentric zone of the cargo container. The security unit also comprises a controller coupled to the positioning receiver and the memory. The security unit is configured to receive the position of the cargo container from the positioning receiver, determine if the position of the cargo container is within one of the first geocentric zone and the second geocentric zone stored in the memory, operate in a first operating mode associated with the first geocentric zone if the position is within the first geocentric zone, and operate in a second operating mode associated with the second geocentric zone if the position is within the second geocentric zone.