Russian Empire Bolsheviks followed in 1918. The administrative boundaries of European Russia, apart from Finland and its portion of Poland, coincided approximately with the natural limits of the East-European plains. In the North it met the Arctic Ocean. Novaya Zemlya and the Kolguyev and Vaygach Islands also belonged to it, but the Kara Sea was referred to Siberia. To the East it had the Asiatic territories of the Empire, Siberia and the Kyrgyz steppes, from both of which it was separated by the Ural Mountains, the Ural River and the Caspian Sea — the administrative boundary, however, partly extending into Asia on
Novaya Zemlya numbering 298, was removed to the mainland in 1957 before nuclear testing began. In 1943, during World War II, Novaya Zemlya briefly served as a secret seaplane base for Nazi Germany's "Kriegsmarine", to provide German surveillance of Allied shipping en route to Siberia. The seaplane base was established by U-255 and U-711, which were operating along the Northern coast of Soviet Russia as part of "13th U-boat Flotilla". Seaplane sorties were flown in August and September 1943. In the months following Hitler’s June 1941 invasion of the Soviet Union, the United States and Great Britain organized convoys of merchant ships