With tensions mounting between Germany and Poland over the future of Danzig, the Germans turned to the Soviets, and signed the Molotov–Ribbentrop Pact, which allowed the Soviets to invade the Baltic states and parts of Poland and Romania. Germany invaded Poland on 1 September 1939, prompting France and the United Kingdom to declare war on Germany on 3 September, opening the European Theatre of World War II. The Soviet invasion of Poland started on 17 September and Poland fell soon thereafter. On 24 September, the Soviet Union attacked the Baltic countries and later, Finland. The British hoped to land at Narvik and send troops to aid Finland, but their primary objective in the landing was to encircle Germany and cut the Germans off from Scandinavian resources. Around the same time, Germany moved troops into Denmark. The Phoney War continued.