Threat detection systems and methods are disclosed that employ position-sensing photodiodes (PSDs) to locate a munitions flash within a field of view of a collection optical system. Image intensifiers are used to form intensified first and second focus spots from the focus spots formed by the collection optical system over two different wavelength bands. The intensified focus spots are then detected by corresponding PSDs. The flash is then located on a map of the monitored terrain, which map can be displayed to a system user. Processing electronics determine whether the flash is actually munitions-based or is from another non-threatening light source.