This book on the problem of the involvement of Rwanda and Uganda in the conflict between the Democratic Republic of Congo and the March 23 Movement is the result of several years of research, reflection and meditation. It is addressed to all those who wish to know the principles of international law in general and that of non-intervention or non-interference in the internal affairs of States in particular for multiple reasons: information, general culture, professional activities, continuing education, etc.The book focuses on the principle of non-intervention or non-interference in the internal affairs of States, i.e. the strict prohibition against intervention by Member States of the United Nations in matters that fall within the competence of a State. He then highlights the involvement of Rwanda and Uganda in the conflict in the Democratic Republic of Congo, i.e. the fact that both UN member states participated in the creation, organisation and financing of M23.