Countdown: M-Day by Tom Kratman.

Just finished it. I don't want to ruin for anyone else, but it's a damn good read. I'm the kinda of guy who usually reads the ending then goes back and finishes the book. The ending is not so important to me as how I get there, but I understand I'm in a minority. This much I'll tell you. Venezuela invades Guyana and finds those "damned gringos" waiting. If you don't want to buy the ARC, the general release is August 30th.