A SAM BATTERY rings the city with surface-to-air missiles.
Its defenders stand at THREE times their strength against aircraft, and keep their FORTIFICATION — though the terrain still counts for nothing from the air.
Against a BOMBER's year of raids, that is the difference between losing a building or two and losing the city's heart.
Requires ROCKETRY. Needs COPPER: +50% shields without.
It answers BOMBERS, REAPER DRONES and CRUISE MISSILES alike.
It does NOT stop a nuclear strike. Nothing does, save the FUSION CORE, which intercepts warheads over the whole empire that holds it.