The volume offers a comprehensive analysis of Church–State relations in post-Soviet Russia, with particular reference to the external relations of the Russian Orthodox Church. The book investigates the impact of the appointment of Metropolitan Kirill of Smolensk and Kaliningrad – now Patriarch of Moscow and All Rus’ – as head of the Moscow Patriarchate’s Department for External Church Relations (DECR), and his contribution to strengthening this branch of the Moscow Patriarchate. It further provides an in-depth analysis of the ecclesiastical crisis in Ukraine, the division of the churches, and the process leading toward unification and the creation of a Ukrainian national church, exploring the implications of this process for the foreign policy of the Russian Federation.