An infrared (IR) security system and method is disclosed comprising two or more IR cameras directed upon a common surveillance area. Locations of the cameras and their optical fields of view are pre-established and stored in a central computer database. Computer programs harmonize the information into a 3D grid. The camera processors perform image processing on the surveillance area to detect moving objects. Object angular position, size, aspect ratio, and radiometric intensity are simultaneously transmitted to the central computer. The grid position, physical size, and inherent electro-magnetic contrast of the objects are computed. These IR signatures are then compared to the target definitions in the database of IR signatures on pre-defined threats. Alarm criteria can be based on object size, location, and movement over time. When a threat is determined, the user is notified by text message, image or video.