A handheld device (e.g., an RFID reader, mobile computer, or the like) is configured to periodically scan its environment for the presence of RFID tags, determine whether any of the RFID tags within range include a valid security code, then disable operation (e.g., by preventing access to stored data) when it is determined that there are no RFID tags with a valid security code within the operational range. The RFID tags may be placed strategically at secure locations within the environment, such as within other network devices (access ports, switches, etc.).