The Sentry programme uses human observers and a network of sensors to compute a predicted impact location when Syrian or allied Russian warplanes take off, triggering air raid sirens and sending warnings to mobile phones

The Sentry programme uses human observers and a network of sensors to compute a predicted impact location when Syrian or allied Russian warplanes take off, triggering air raid sirens and sending warnings to mobile phones https://t.co/zVpXUjfpGh

— AFP news agency (@AFP) August 30, 2018

Source: Twitter