Scandinavian defence union

The Scandinavian defence union was a historical idea to establish a military alliance between Sweden, Norway, Denmark and Finland (although not a Scandinavian country) after the end of World War II, but the idea did not come about when Denmark, Iceland and Norway joined NATO in 1949 at the request of the United States, while Finland and Sweden then did not. Historically, Finland had fought two wars against the Soviet Union, Denmark and Norway had been occupied by Germany between 1940 and 1945, and Sweden, having been a neutral state throughout the war, had still felt the effects on either side.

Source: Wikipedia — Scandinavian defence union (CC BY-SA 4.0)