Cauldron tactic

The condition for the cauldron is a bulge of enemy forces in tactical encirclement or open cauldron, which can pursue different objectives like to lure more reinforcements or on the contrary to force the most out picking on heavy equipment moving through limited controlled routes in process.
Control over routes of retreat and reinforcement and destruction of enemy armor.
Closing the lid.
Setting to boil.
Once the conditions are right, the cauldron is locked, by severing the above controlled routes and ‘set to boil', meaning the enemy can't retreat or get resupplied while subjected to heavy fire with the objective to destroy or force mass surrender.
The enemy surrenders.
Cauldron is a name for such situation involving thousands of forces, but it can be implemented down to a company level. That's then called sack and the enemy in this case is bagged.

https://www.quora.com/Can-someone-with-Russian-military-experience-explain-the-Russian-cauldron-tactic-Is-it-simply-encirclement-and-cutting-off-logistics-or-is-it-more-complicated-than-that