After signing the Molotov–Ribbentrop Pact and German–Soviet Frontier Treaty, the Soviet Union forced the Baltic countries—Estonia, Latvia, and Lithuania—to allow it to station Soviet troops in their countries. Finland rejected territorial demands, prompting a Soviet invasion in November 1939. The resulting Winter War ended in March 1940 with Finnish concessions. Britain and France, treating the Soviet attack on Finland as tantamount to its entering the war on the side of the Germans, responded to the Soviet invasion by supporting the USSR's expulsion from the League of Nations.