President Lincoln found it necessary to hire a private investigator - Alan Pinkerton - for protection. That was the beginning of the Secret Service. Since that time federal police authority has grown to a large number of multi-letter agencies - FBI, CIA, INS, IRS, DEA, BATF, etc.
Now comes the "Federal Air Transportation Airport Security Service. " Can't you see them now, these highly trained men and women in their black outfits with their initials in large white letters across their backs: "FATASS."
I feel safer already!