Deep underground military bases or DUMBs as the military calls them. 131 of them were built by 1996. 62 of them were allocated to the aliens to live in. Each one cost around 18 billion each. 131 x 18b = 2.3T The same amount of money missing on 9/10/2001. Also Project Excalibur and Project Joshua were specifically designed to kill the aliens in the dumbs!