Baltic Sea. Mannerheim was elected regent by the Eduskunta, and Finnish policy became pro-Entente as the western powers intervened in the Russian Civil War (7 November 1917 – 16 June 1923). Mannerheim favoured intervention against the Bolsheviks but suspicion of the White Russians who refused to recognise Finnish independence led to his aggressive policy being overruled; then, the Bolshevik victory in Russia forestalled Finnish hostilities. Paasikivi led a delegation to Tartu, in Estonia, with instructions to establish a frontier from Lake Ladoga in the south, via Lake Onega to the White Sea in the north. The importance of the Murmansk railway, built in 1916, led the Soviet delegation to reject the Finnish border proposal, and the treaty of 14 October 1920 recognised a border agreement in which Finland obtained the northern port of Petsamo (Pechenga), an outlet to the Arctic Ocean, and a border roughly the same as that of the former Grand Duchy of Finland. Claims on areas of Eastern Karelia were abandoned and the Soviets accepted that the south-eastern border would not be moved west of Petrograd. Winter War During the Interwar period, relations between Finland and the Soviet Union were tense. Some elements in Finland maintained the dream of a "Greater Finland" which included the Soviet-controlled part of Karelia, while the proximity of the Finnish border to Leningrad (now Saint Petersburg) caused worry among the Soviet leadership. On 23 August 1939, Nazi Germany and the Soviet Union signed the Molotov–Ribbentrop Pact, which included a secret clause demarcating Finland as part of the Soviet sphere of influence. On 12 October the Soviet Union began negotiations with Finland regarding the disposition of the Karelian Isthmus, the Hanko Peninsula, and various islands in the Gulf of Finland, all of which were considered by the Finns to be Finnish territory. No agreement was reached. On 26 November the Soviet Union accused the Finnish army of shelling the village of Mainila. It was subsequently found that the Soviets had in fact shelled their own village, in order to create a pretext for withdrawal from their non-aggression pact with Finland. On 30 November 1939, the Soviet Union attacked Finland. The attack was denounced by the League of Nations, and as a result, the Soviet Union was expelled from that body on 14 December. The aim of the invasion was to liberate the 'Red Finns' and eventually annex Finland to the Soviet Union. To