A system and method for highly selective intrusion detection using a sparse array of ultra wideband (UWB) radars. Two or more UWB radars are arranged in a sparse array around an area to be protected. Each UWB radar transmits ultra wideband pulses that illuminate the area to be protected. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the area to be protected. This image is used to detect motion in a highly selective manner and to track moving objects within the protected area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.