Departing from the observation that traditionally the law of State responsibility has hardly interacted with the law of territory, the article examines how these two fields of international law may relate in the case of State action in contested areas, be they terrestrial or marine. Assessing recent international practice, particularly the case law of the International Court of Justice and arbitral tribunals, and differentiating between land and maritime disputes, it identifies the primary obligations incumbent upon States when acting in contested areas - relating to State sovereignty and sovereign rights, ius ad bellum, ius in bello, procedural obligations pending the final settlement of the dispute - and it examines the consequences of the breach of those primary norms, in terms of secondary obligations, as well as third States' duties and obligations. The legal framework specifically created for disputed maritime areas by Art. 74 para. 3 United Nations Convention on the Law of the Sea (UNCLOS) and Art. 83 para. 3 UNCLOS, including its implications for land disputes, is specifically analysed. The authors submit that, at a time of increasingly pro-active policies and robust actions taken by States in contested areas, more attention should be devoted to the extent to which the law of State responsibility, especially with regard to relevant forms of reparation, has to adapt to the content and scope of primary norms applicable to that specific context.