Nucelar Warheads in Supreme Commander 2 are devastating weapons used to destroy mainly bases. They are expensive though, but most consider it worth it.
Every faction uses different warheads fired from different facilities. The UEF fires a blue warhead from a flat, 4 silo launch facility. The warhead itself resembles a blue crayon.
The Illuminate fire an enormous charged sphere of superheated plasma from a vertical silo. The warhead gives of a blue light and resembles a comet.
The Cybran Nation fires a fast moving, V2 rocket-like warhead which trails a red fuel burn. It is fired from a spiked, triple silo facility. Every warhead creates the same damage, effect, and sound effect, but their appearances change between factions.