you dont send the choppers in until the air defence is neutered. What do you think a few dozen specaial forces are doing in Caracas?
Presumably there are SF and/or airborne units executing coordinated strikes on the ground right now. Most likely the 160th, as they were deployed there last I checked.
As you say, this check has been in the mail for a while, so how are vulernable helicopters flying over caracas without any resistance? One dude with a MANPADS could take them down.
Decapitation is also the only aparent strategic goal of this operation, so it's hardly far fetched to suggest they going for 'one and done'.
Anyway, beers on me if I'm wrong :)