The Manchurian Candidate.

Years after his squad was ambushed during the Gulf War, Major Ben Marco finds himself having terrible nightmares. He begins to doubt that his fellow squad-mate Sergeant Raymond Shaw, now a vice-presidential candidate, is the hero he remembers him being. As Marco's doubts deepen, Shaw's political power grows, and, when Marco finds a mysterious implant embedded in his back, the memory of what really happened begins to return.