Military crime fiction is usually considered a sub-genre of the espionage thriller genre. But there are also thrillers featuring crimes committed within the military. Some authors use former soldiers that have become detectives or special operatives as their leading character.
Famous authors of military thrillers include Lee Child, Tom Clancy, Jack Higgins, Alistair MacLean, Stephen Coonts, Dale Brown, W.E.B. Griffin, or Harold Coyle.More on Wikipedia