Sweden has for a long time consistently adhered to defence doctrines emphasizing the need for a large, conventional anti-invasion defence in which army and air strength is neatly balanced and supplemented with a relatively weaker navy. Nuclear arms have been rejected and the nuclear threat, in the official defence doctrines, attributed only little probability. The fact that a stranded, obsolete, Sovjet submarine trespassing on Swedish territorial waters is likely to have carried nuclear arms has released strong emotions but hardly changed this evaluation. Recent experiences have indicated the existence of a very different threat, based on the vulnerability of the modern industrial society, against not only various forms of destruction but also major international disturbances without direct bearing on the Swedish society. Much in the contemporary debate deals with these issues, and much in the political conflict concerns different evaluations of security and defence, of old threats and new threats.