Denmark–Russia relations (alternatively: Dano-Russian relations) are the relations between the two countries of Denmark and Russia. The Kings of Denmark and the Russian Tsars interacted from the 15th century onwards - subsequently Denmark's control of access to and from the Baltic Sea had considerable significance for the trade and naval flexibility of the Russian Empire, while rivalries between Denmark and Sweden on the one hand and between Sweden and Russia on the other led to alliances and military support. Denmark and the USSR established diplomatic relations on 18 June 1924.