A security sensor system comprises one or more laser detection and ranging (LADAR) sensors configured for accumulation of three-dimensional image data. In one embodiment, the one or more LADAR sensors each comprise a LADAR device, such as a MEMS device, configured to transmit a plurality of laser pulses, and a microprocessor operatively coupled to the LADAR device. One or more data storage devices is operatively coupled to the microprocessor and configured to store the three-dimensional image data, as well as predetermined protected area boundary and fixed object definitions. A GPS receiver can be operatively coupled to the microprocessor and a GPS antenna. The microprocessor is configured to perform a LADAR image analysis that compares the three-dimensional image data with the protected area boundary and fixed object definitions to identify one or more potential intruders.