As a constituent part of the Soviet Union, tensions lessened over the ethnic composition of Nakhchivan or any territorial claims regarding it. Instead, it became an important point of industrial production with particular emphasis on the mining of minerals such as salt. Under Soviet rule, it was once a major junction on the Moscow–Tehran railway line[14] as well as the Baku–Yerevan railway.[2] It also served as an important strategic area during the Cold War, sharing borders with both Turkey (a NATO member state) and Iran (a close ally of the West until the Iranian Revolution of 1979).