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 are still used for airfields today. The Soviet Air Force maintained a presence at Rogachevo on the southern part of the southern island, on the westernmost peninsula (). It was used primarily for interceptor aircraft operations, but also provided logistical support for the nearby nuclear test area. Novaya Zemlya was the site of one of the two major nuclear test sites managed by the USSR, used for air drops and underground testing of the largest of Soviet nuclear bombs, in particular the October 30, 1961 air burst explosion of Tsar Bomba, the largest, most powerful nuclear weapon ever detonated. The