支援(Backup) Backup in tactical operations means the operation of firearms ready for shooting while performing a duty. It is important for self-defense of involved agents and to prevent escapes. It is done by pointing to a target or shooting. Back up may lead, but is not limited, to suppressive fire.
The purpose of Back up fire is to cover an operation of one or several agents such as entering a room or arresting a suspect or fugitive.
It is important that own agents or other innocent people are not standing, or moving through, the line of fire.
Leapfrogging, Bounding Overwatch) A typical application uses suppressive fire to advance a group of attackers against an enemy:
To stop the enemy from shooting at attackers, the attacking force divides in two.
The first group of attackers fires on the enemy. This will cause the enemy to take cover, thus minimizing their ability to return fire.
While the first attacking group is firing at the enemy - keeping them suppressed - the second group of attackers advances toward the enemy position.
This second group now stops, and begins laying down their own suppressive fire. The first group can now advance under cover of the second group's suppressive fire.
The process repeats as needed, with each attacking group alternating roles (either advancing or laying down suppressive fire) until they can attack the defenders at close quarters, also called leapfrogging.