Sweden helped Finland with arms and volonteers during their war with the Soviet Union (my grandfather did two tours), and Sweden covertly trained the norwegian resistance, and offered asylum to all norwegian refuges except those who where communist resistance, they were turned over to the gestapo. Swden traded heavily with Germany and Germany recieved something like 80 per cent of its iron ore from Sweden, Sweden also allowed Germany to transfer troops from Norway to Finland (so they could fight the russians) thru Sweden.

After the war Sweden claimed to be strictly neutral, after failed attempts to form a defensive pact with the other nordic countries, but that neutrality was just a show as there was no doubt the only possible aggressor would be the Soviet Union, and technical preparations were made to join forces with Nato in the event of an attack.

Sweden participated with both army and air force units in Kongo in 1960 under UN command.

Sweden joined the EU in the early 90's and wouldn't stay neutral if another memberstate was attacked. Sweden also gave military aid (surplus materiel) to the Baltic states in the 90's, so that they could build a fledgling army and so that shots would actually be fired if Russia invaded them again.

Sweden has a battle group together with Estonia, Finland, Norway and Ireland, we contribute with 2300 soldiers and this group is supposed to go online in 21 days from today, to be ready to deploy within 6000 km from Brüssels. Either they go to Sudan or to Kosova.

There is also talk about Sweden and Finland joining their marines, and a common nordic air defence.

So in conclusion, Sweden is hardly neutral anymore.