Abstract: Methods and apparatuses are provided, for use singlely, or as part of a comprehensive security solution, for ensuring the integrity of a supply chain involving transportation, storage and/or sale of fluids such as petrochemicals. Passage of a fluid through an opening in an otherwise closed fluid tank is controlled by locking the opening against passage of fluid therethrough until a signal derived from a GPS is received, indicating that the tank is positioned at a pre-determined location whereat the opening in the tank is to be unlocked for allowing passage therethrough of the fluid. The tank may be, inter alia, a mobile tank, a stationary tank at a bulk station, or a stationary tank at a service station.