were the last German troops to surrender after the Second World War. After the war, the Soviet Union proposed common Norwegian and Soviet administration and military defence of Svalbard. This was rejected in 1947 by Norway, which two years later joined NATO. The Soviet Union retained high civilian activity on Svalbard, in part to ensure that the archipelago was not used by NATO. Post-war After the war, Norway re-established operations at Longyearbyen and Ny-Ålesund, while the Soviet Union established mining in Barentsburg, Pyramiden, and Grumant. The mine at Ny-Ålesund had several fatal accidents, killing 71 people while it was in operation from 1945 to 1954 and from 1960 to 1963. The Kings Bay Affair, caused by the 1962 accident killing 21 workers, forced Gerhardsen's Third Cabinet to resign. From 1964, Ny-Ålesund became a research outpost, and a facility for the European Space Research Organisation. Petroleum test drilling was started in 1963 and continued until 1984, but no commercially viable fields were found. From 1960, regular charter flights were made from the mainland to a field at Hotellneset; in 1975, Svalbard Airport, Longyearbyen opened, allowing year-round services. During the Cold War, the Soviet Union comprised about two-thirds of the population on the islands (Norwegians making up the remaining third) with the population of the archipelago slightly under 4,000. Russian activity has diminished considerably since then, falling from 2,500 to 450 people from 1990 to 2010. Grumant was closed after it was depleted in 1962. Pyramiden was closed in 1998. Coal exports from Barentsburg ceased in 2006 because of a fire, but resumed in 2010. The Russians experienced two air accidents: Vnukovo Airlines Flight 2801, which killed 141 people, and the Heerodden helicopter accident, which killed three people. Longyearbyen remained purely a company town until 1989 when utilities, culture, and education was separated into Svalbard Samfunnsdrift. In 1993, it was sold to the national government and the University Centre was established. Through the 1990s, tourism increased and the town developed an economy independent of Store Norske and mining. Longyearbyen was incorporated on 1 January 2002, adopting a community council. Population Demographics In 2016, Svalbard had a population of 2,667 of which 423 were Russian and Ukrainian, 10 Polish, and 322 non-Norwegians living in Norwegian settlements. The largest non-Norwegian groups in Longyearbyen in 2005 were from Russia, Ukraine, Poland, Germany, Sweden, Denmark, and Thailand. Settlements Longyearbyen is the largest settlement on the archipelago,