Territorial integrity is a well-known principle of international law, which gives rise to the highest controversy.Namely, states' right to defend themselves before threats posed by other states, especially by non-state actors.The question is how territorial integrity should be interpreted against the background of new threats to peace and security brought by terrorism.Author examines customary law and United Nations Charter and their influence on the perception of territorial integrity of states.What alternatives do states have in answering to acts, which threatens their territory or...