Jack Carr is a former Navy SEAL sniper (enlisted and officer) and best-selling author in both fiction and non-fiction. His latest, "Cry Havoc", is sort of a pre-prequel of the "Terminal List" series, focusing on Tom Reece, the father of the Terminal List's protagonist, James Reece, during the elder Reece's military service in the Vietnam War.
This is a GREAT thriller. I'd put it near or at the top of Jack's books and I thoroughly recommend it!