The Bering Strait was a strait running between East Russia and Alaska, (PROSE: Doctor Who: The Encyclopedia) the latter of which was called the "stepping stone between America and Asia" by the Fifth Doctor. (AUDIO: The Land of the Dead)
During the Year That Never Was, the Master and the Toclafane turned Russia into the massive Shipyard Number One, which ran from the Black Sea to the Bering Strait. (TV: Last of the Time Lords)