The puppet strings you refer to are trade (and other economic development) agreements.
The other Scandinavian countries may not have had such close ties to the US as Sweden, however US-Sweden relations have a rich and storied history[1] stretching back quite far (with particular emphasis on defense against Soviet aggressions).
The other Scandinavian countries may not have had such close ties to the US as Sweden, however US-Sweden relations have a rich and storied history[1] stretching back quite far (with particular emphasis on defense against Soviet aggressions).
[1] http://en.wikipedia.org/wiki/US-Sweden_relations