The Russia-Ukraine war is the most significant armed conflict of the twenty-first century in terms of countries involved, casualties inflicted, and actual and potential impact not only in Ukraine and Russia but in many other countries. Its outcome is likely to shape the world order. Truth is the first casualty of war. The Ukraine war and previous conflicts in Ukraine produced divergent narratives by the governments and the media in Ukraine, Russia, and the West. However, the governments and the media are often unreliable sources. The book advances scholarly research on the Russia-Ukraine war and its origins in a systematic and evidence-based way. It is based on an analysis of tens of thousands of mostly primary sources in Ukrainian and Russian.