The CIA has been smuggling dope at least as far back as 'Nam. They use the money for Black Ops programs that have no accountability to Congress. Tell me that the head doesn't know what's going on and I'll call you a liar. This government is corrupt and it goes back a long time. It has nothing to do with which party is in power as both are controlled by the same corrupt financial interests.
If anyone has blackmailed Petraeus it's Obama's corrupt Chicago gang... "either lie for us at the Congressional hearings or we go public with your affair, which BTW, we've known about for months... and you're toast!"