In modern warfare, overwatch is a force protection tactic: the state of one small unit or military vehicle supporting another unit, while they are executing fire and movement tactics. An "overwatching", or "supporting" unit has taken a position where it can observe the terrain ahead, especially likely enemy positions. This allows it to provide effective covering fire for advancing friendly units. An ideal overwatch position provides cover for the unit, and unobstructed . It may be on a height of ground or at the top of a ridge, where a vehicle may be able to adopt a hull-down position. If the overwatching unit is in a position to fire over advancing friendly units, great care must be taken not to let fire fall short. The friendly units should be within tracer burnout (the range at which tracer rounds are visible).