Arctic Circle level, although in mountainous regions there is often no direct view of the true horizon. Only four million people live north of the Arctic Circle due to the severe climate; nonetheless, some areas have been settled for thousands of years by indigenous peoples, who today make up 10% of the region's population. Tens of thousands of years ago, waves of people migrated from eastern Siberia across the Bering Strait into North America to settle. The largest communities north of the Arctic Circle are situated in Russia, Norway and Sweden: Murmansk (population 307,257), Norilsk (175,365), Tromsø (71,295), Vorkuta (59,231) and Kiruna
Arctic policy of Russia nuclear icebreaker, the "Lenin", began operating in the Northern Sea Route in July 1960. A total of ten nuclear-powered civilian vessels, including nine icebreakers, have been built in Russia. Three of these have been decommissioned, including the "Lenin". Besides its six nuclear icebreakers, Russia also has 19 diesel polar icebreakers. Its nuclear icebreaker fleet includes the "50 Let Pobedy" (50 Years of Victory), the largest nuclear icebreaker in the world. There are currently plans to build six more icebreakers, as well as plans to build a $33 billion year-round Arctic port. On September 28, 2011, President Medvedev lifted the ban