In international law, there is a dispute over whether military operations by foreign troops in internal conflicts, which are not based on a mandate from the United Nations Security Council, are permissible under international law. In his book, Nolte explores the question of whether the invitation of the respective government can serve as a legal basis for such operations. He examines the significance of the relevant fundamental principles of international law (consent, prohibition of intervention, prohibition of the use of force, right to self-determination, protection of human rights, recognition of governments) and then analyzes the extensive state practice. The result of his analysis is that the invitation of the government can be justifiable within certain limits and is compatible with the fundamental principles of collective security as they have developed since the end of the Cold War.