By Paul Giotta
After 9/11 the White House had torrent style high powered artillery you see on warships installed on the roof of one of the buildings just north of the complex.
These high powered weapons built specifically to bring down airplanes are manned by military personnel trained to fire such a weapon, not secret service agents. The movie Olympus has fallen portrays how this weapon would work rather well except for the fact that in real life no plane would be able to reflect all of the rounds being fired at it.
I would go into greater detail about how the military and secret service work together to make sure there is no rogue member of either that starts blasting away at planes landing or taking off from Reagan, but unfortunately the nature of my work prevents me from doing so.