An interesting paper: 'Lying in International Politics' by John J. Mearsheimer. He says that lying is an accepted feature of international relations as statesmen obviously believe that lying sometimes has utility.
He spells out 4 different forms of lying:
"Inter-state lying is where states lie to each other to gain strategic advantage. Fear-mongering is where foreign policy elites lie to their own public because they believe that the people do not recognize the seriousness of an external threat and they need to be motivated to deal with it. Nationalist myth-making is where elites tell lies about their state’s history to help foster a powerful sense of national identity among all segments of society. Anti-realist lying is where elites attempt to disguise brutal behavior carried out in pursuit of realist (or other) goals, because it conflicts with widely-accepted liberal norms."