The main task of the directorate is to improve Norway’s ability to protect itself against espionage, sabotage, terrorism and hybrid threats. 

Through advice, control activities, supervision, security testing and security research NSM shall help organisations to protect civilian and military information, systems, objects and infrastructure that are relevant to national security. NSM is responsible for a national cyber warning system for critical infrastructure (VDI) that detects and warn of cyberoperations against digital infrastructure. NSM also has a national responsibility for coordinating the handling of serious cyberoperations. The National Cyber Security Centre (NCSC-NOR) is part of NSM. 

NSM is administratively subordinate to the Ministry of Justice and Public Security. In addition, the Ministry of Defence has authority of NSM with respect to their area of responsibility.