The Bunker is a building used to garrison troops for defence.
The bunker cost $100 to build and has no additional requirements other than the basic ones of having a building near where the bunker is to be built.
The bunker can be used to garrison up to 10 ground troops. it has high defence but sadly, does not attack. Should only be used to store troops at plants for defending a plant.
In my opinion, the bunker is not necessary, because if a nuke is coming to, you could easily spread your troops, making it harder for the enemy to use the nukes against units.