This chapter describes how Russian information warfare is changing and what challenges the poses for international law. It outlines the particularities of the Russian understanding of warfare and what has shaped this understanding. The chapter reviews the development in the information-psychological and the information-technical aspects of information warfare respectively. The information-technical domain of information warfare is concerned with the machine-driven data components, the means of transmission, and the information infrastructure. The possibilities within international law to counter information-psychological warfare are quite meagre. In the Vilnius regional court in Lithuania, action has been taken against Russian information warfare. In the war in Ukraine, Russia has showed an effective and well-coordinated effort on the information warfare front. The success of Russian information warfare is a development resulting from the bitter experiences on the information front during the First Chechen War in 1994–1996.The character of contemporary warfare has recently undergone significant transformation in several important respects: the nature of the actors, the changing technological capabilities available to them, and the sites and spaces in which war is fought. These changes have augmented the phenomenon of non-obvious warfare, making understanding warfare one of the key challenges. Such developments have been accompanied by significant flux and uncertainty in the international legal sphere. This handbook brings together a unique blend of expertise, combining scholars and practitioners in science and technology, international law, strategy and policy, in order properly to understand and identify the chief characteristics and features of a range of innovative developments, means and processes in the context of obvious and non-obvious warfare.