The use of the word heartland could be a warning, could be a message, could be a figurative use of the word, i.e., the heart of the country, the heart of the economy. Could be code. Wherever they strike they'll want to have maximum impact on the economy. Houston comes to mind. And isn't that a big cardiology center? hmmm....dum de da dum
I don't think so.........they will not wipeout any Large or Small "Mexican" city centers! ANYWHERE!!
'Heartland'=Any Government Staffed Buildings!
'Heartland'= The "Buildings" of Bureaucracy and its Related Components/Extentions!
EVERYWHERE!
IMHO