In 1914, however, the Russian government turned the islands into a submarine base for the use of British and Russian submarines during the First World War. In December 1917, the Finnish government proclaimed that Finland was a sovereign state and a dispute over whether the islands belonged to Sweden or Finland ensued. In 1921, again despite the fact that almost 100 percent of the islands' population was Swedish—and that they expressed a desire of being incorporated into Sweden—the League of Nations decided that the Åland Islands should remain a part of Finland.