While geographically not close, two countries were both predominantly Slavic with significant shared Eastern Orthodox Christian traditions which were particularly reflected in historical pre-World War I relations between Russian Empire with Principality of Serbia and Principality of Montenegro. Significant historical, cultural and political links were nevertheless not reflected in close bilateral relations with tensions and strategic divisions continuing almost throughout the existence of Yugoslavia and the Soviet Union. It was not until June 1940 that the Kingdom of Yugoslavia formally recognised the USSR and established diplomatic relations,[2] one of the last European countries to do so.[3]