The matter of German troop transfer through Finland and Sweden during World War II was one of the more controversial aspects of modern Nordic history beside Finland's co-belligerence with Nazi Germany in the Continuation War, and the export of Swedish iron ore during World War II. The Swedish concession to German demands during and after the German invasion of Norway in April–June 1940 is often viewed as a significant breach with prior neutrality policies that were held in high regard in many smaller European nations. After they were publicly acknowledged, the Soviet Union immediately requested a similar but more far-reaching concession from Finland, which invited the Third Reich to trade similar transit rights through Finland in return for weaponry lacked by the Finns. This was the first significant proof of a changed, more favorable, German policy vis-à-vis Finland, that ultimately would put Finland in a position of co-belligerence with Nazi Germany in the Continuation War against the Soviet Union (25 June 1941 – 4 September 1944). German troops through Sweden After Denmark and Norway were invaded on 9 April 1940, Sweden and the other remaining Baltic Sea countries became enclosed by Nazi Germany and the Soviet Union, then on friendly terms with each other as formalized in the Molotov–Ribbentrop Pact. The lengthy fighting in Norway resulted in increased German requests for indirect assistance from Sweden, demands that Swedish diplomats were able to fend off by reminding the Germans of the Swedes' feeling of closeness to their Norwegian brethren. With the conclusion of hostilities in Norway this argument became untenable, forcing the Cabinet to give in to German pressure and allow continuous (unarmed) troop transports, via Swedish railroads, between Germany and Norway. The extent of these transports was kept secret, although spreading rumors soon forced prime minister Per Albin Hansson to admit their existence. Officially the trains transported wounded soldiers and soldiers on leave (permittent-tåg), which would still have been in violation of Sweden's proclaimed neutrality. In all, close to 100,000 railroad cars had transported 1,004,158 military personnel on leave to Germany and 1,037,158 to Norway through Sweden by the time the transit agreement was disbanded on 15 August 1943. After the German invasion of the Soviet Union in early summer of 1941, Operation Barbarossa, the Germans on 22 June 1941 asked Sweden for some military concessions. The Swedish government granted these requests for logistical support. The most controversial concession was