future. here's how it works. north korea launches -- >> impact, location. this is los angeles. we are engaging this threat at this time. >> reporter: -- instantly activating a room in fort greeley. what you're seeing now is a drill declassified so we can show you generally how the ground intercepters work to protect the u.s. >> as the alarms would go off, what you would see is the white shells you see behind us would separate extremely quickly and immediately you'd see a flash of flame as that gbi would leave the tube at an incredible rate of speed. >> reporter: if it works, the interceptor kills the incoming nuclear weapon. >> we train to shoot a bullet at a bullet and destroy it and destroy it so it doesn't destroy us. >> has it taken on new meaning? >> what it does is makes it more