The Internet has become the most essential means of communication and information. This results in a high dependency upon reliable operations of Internet based communication systems, especially thos supporting critical infrastructure systems. Given the shortcomings of the Internet with regard to security, the vulnerability of computer systems has become a significant matter of (national or collective security to many states as well as to NATO. The potential conduct of "computer network operations" (CNO), i.e. military defensive or offensive actions taken by the means of the Internet or other computer networks, presents some legal challenges. This survey first examines the nature of CNO and discusses the difficulties of identification of the origin and of atribution of a malicious action carried out via or in the cyberspace to a certain actor. After the presentation of some criteria for the qualification of CNO as "use of armed force" (in the ius in bello meaning), the survey argues that the laws of armed conflict, including the over hundred years old principles and provisions of neutrality, do apply to CNO. A the same time, it demonstrates that the provisions offer a level of humanitarian protection comparable to that applicable to the use of conventional weapons.