The Stinger MANPADS are part of the protection package deployed by the Secret Service protection detail for the President where ever he goes. And IIRC they are even carried on one of the Tahoe SUV's in the motorcade.
After 9/11 They put an AN/TWQ-1 Avenger which is essentially a Humvee with a turret holding two four round stinger pods on the top of one of the building oat the Navy Annex to protect the South side of the Pentagon.
