A crime against peace, in international law, refers to "planning, preparation, initiation, or waging of wars of aggression, or a war in violation of international treaties, agreements or assurances, or participation in a common plan or conspiracy for the accomplishment of any of the foregoing".Nicolas Werth, Karel Barto?ek, Jean-Louis Panné, Jean-Louis Margolin, Andrzej Paczkowski, Stéphane Courtois, The Black Book of Communism: Crimes, Terror, Repression, Harvard University Press, 1999, hardcover, 858 pages, ISBN 0-674-07608-7, page 5.