Preparations for the start of the Third Tiberium War required a very high degree of secrecy. The need for concealment and stealth coupled with the ever-increasing number of Ion Storms has forced the Brotherhood to move away from airlift as the primary source for reinforcements for combat units.
The Brotherhood is employing the ultimate in "Just in Time" weapons delivery: vehicles are built inside on-site war factories, housed mostly underground. They use nano-assemblers and heavy industrial robots to construct and repair tanks, bikes, buggies, and other vehicles. Repair drones orbit around the surface of the factory, repairing any nearby vehicles.
The War Factory does have some unique characteristics including a lift that spins the vehicle up to ground level.
The back end of the structure contains a tower that rises when it is constructing a vehicle and then lowering again after it has completed its building queue