Remember when the Vietcong took over Huế? They were able to round up every government official, march them all off into the jungle and kill every single one of them in one night
They knew exactly where they lived, who they visited, where they shopped and where they ate dinner, and when.
How you ask?
The cabbies had been providing the data on their every move for years in advance.
Soooo, where do most of the cabbies in your berg come from? In Washington DC, it's Somalia...
Just because we've forgotten the lessons of Huế and the lessons of the Sepoy Rebellion's "The Perfect Day" doesn't mean our enemies have.
The DC-area cabbie in my comment above is a Somalian immigrant.