Your Base's emergency survival bunker is a reinforced subterranean shelter where you may secure your fighting forces and Resources. Units and Resources inside the Bunker will be protected in the event of a Raid or Occupation.
The bunker is already supplied when starting the game and cannot be built, only upgraded. Subsequent upgrades protect more resources from an attacking enemy, up to a maximum of 18,000 of each resource type at Bunker Level 20.
Note: Thulium, Diamonds, Equipment and Stims cannot be raided and are fully protected regardless of the Bunker Level
Scale of Resource Protection