Konsab was a commander in the Romulan military in the 24th century who taught Military History at the Intelligence Academy. One of his main themes was the difference between the military and the Tal Shiar. He believed that, in order for a military to function, its officers must trust each other. By contrast, the Tal Shiar trust no one, and always found deception because they expected it.
Commander Toreth mentioned Konsab's teachings to Deanna Troi when she was posing as Major Rakal aboard the IRW Khazara in 2369. (TNG: "Face of the Enemy")