The new information society has revolutionised almost the entire world. But the new technique does not only bring good. That which was before only available on paper may today only be available on a computer system. This makes it possible to send data electronically. In the wrong hands that information can become a threat against the security of an individual, a company or even a nation. The possibility to protect oneself against attacks from the outside becomes increasingly difficult. There are a lot of factors involved but a major factor is the fast technical development we now see within this area. Our defence minister, Björn von Sydow, writes in an article that it is almost impossible to protect one self against the unexpected. Björn Andersson (SÄPO) says as well that there are no secure systems, only more or less easy penetrable systems for the attacker to attack. The threat against Sweden is quite diffuse. The old threat of invasion is no longer which can make it difficult to identify a specific threat. The word of the governments today is terrorism. The purpose of our paper, considering this background, is to take a look at the possible threats against swedish information systems and to see the seriousness of the threats these systems are facing. It mainly consists of systems for ensuring we are provided with power and water and that finance and communication works. The questions that we ask ourselves are if information warfare indeed is a threat ? Who are the attackers and what drives them to perform the actions they perform ? Which are the targets they aim their attacks against ? Are the techniques behind information warfare realistic and is there really a threat, or is it all just blown out of proportions ? To get answers to our questions we have gone through a lot of material. A lot of it was downloaded from the Internet and has been of varying character. We have also been given a lot of material from our government and we have read some literature about the area of interest. We have finally done some interviews with staff from Lunds Energi, Skanova Networks and Säkerhetspolisen.