Operation Weserübung's effects on Sweden became strategically encircled by the German-Soviet pact. Since the Baltic states; Estonia, Latvia, and Lithuania; had been forced to accept "limited" Soviet forces on their soil, in the autumn of 1939, they were de facto more or less in a state of occupation. For Sweden and Finland, this meant that the only possible trade route to nations other than Germany and the Soviet Union, was through Petsamo harbour, in the far north of Finland. This seriously hampered the supply situation in both these nations. It also meant that an invasion of Sweden could be launched from almost any direction. Sweden
Finland–Russia border Finnish reindeer fence. Unlike other Western countries, the government of Finland did not protect illegal border crossers but returned them to the Soviet authorities if captured. Illegal border crossers had to get through Finland to e.g. Sweden in order to defect to the West. In the Moscow Armistice signed on 1944 between Finland, Soviet Union and United Kingdom, a small peninsula towards the Gulf of Finland, Porkkala, was rented to Soviet Union as a military base. This created in effect a southern border crossing to the Soviet exclave, operating all the way to 1956. Border crossings were in and .