There have been three other Nordic cooperation efforts, on the military side. The first was in 1948 (IIRC) when Sweden tried to create a Nordic military alliance. For obvious reasons, including the way Sweden gave Finland unofficial military guarantees during the 30's just to abandon them when push came to shove, this came to naught.

During the Cold War there were plenty of secret military cooperation between the Nordic countries, which I won't delve deeper into here, beyond noting that a free and independent Sweden was crucial for the security of Norway, just as a free and indepent Finland (and Baltic states) are crucial for the security of Sweden. And obviously, a free and independent Norway is crucial for the security of the Atlantic convoys in WWIII, and hence crucial for the security of West Germany. Anyway, many crucials there.

The third bout of military cooperation has begun in the last few years. Let me quote from that article in TWS:

Sweden is presently the driving force behind the Nordic Cooperation movement, an attempt to develop an integrated defense and industrial policy covering Sweden, Norway, Finland, and the Baltic States. This has picked up significant momentum in the last few years, in part because of the experience of the Nordic Battle Group, in part because of the recognition that these technologically advanced but sparsely populated countries cannot afford to field large forces individually, and finally, because of the recent rumblings of the Russian bear. Already the Nordic Cooperation group is engaged in joint system development and procurement, joint planning and exercises, and is moving towards some degree of specialization and division of labor in defense tasks.

Denmark is also taking some part in this.

Peak oil is not an energy crisis. It is a liquid fuel crisis.