The Sentry Gun is Soviet Union's basic base defense structure. It is basically three heavy machine guns on a 360-degree turning mount, surrounded by brick and mortar and manned by a single Conscript. The machine guns appear to fire armor piercing bullets, as it is very deadly against both infantry and light vehicles, and can even be a threat to tanks in large numbers. These structures offer a somewhat cost effective resistance against lone commando assaults (Natasha's laser sight has less range than its machine guns), but are out-ranged by artillery units and defenceless against aircraft.