Transit of German troops through Scandinavia (WWII)

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 badly needed 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 (June 25, 1941 – September 4, 1944).

After Denmark and Norway were invaded on April 9, 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 intensified German demands for indirect support 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.

...
Wikipedia