Abstract: Methods, computer-readable media, and systems for externally cued aircraft warning and defense are disclosed. A surveillance system may include a sensor field or array and may include a processor system that processes signals including acoustic signals received by the sensor array. Signals including acoustic signals are processed to determine the presence of indicia, including acoustic signatures, of known surface-to-air missiles including man-portable air defense systems. When the presence of such surface-to-air missiles is indicated, a cue signal is sent to one or more countermeasure systems that include one or more countermeasures such as chaff, expendable decoys and flares. The countermeasure systems may be ground-based or aircraft-based. The countermeasures are deployed in response to the cue signal. The surface-to-air missile may consequently be defeated.