This paper on “Security of the maritime traffic monitoring and information system” gives an analysis and an overview of main elements of a complex system such as the VTMIS. It explains its processes and activities, and the importance of its work. The Republic of Croatia is a maritime country, a member of the European Union, with tourism as the strongest economic branch. That means Croatia should never neglect areas that deal with maritime security on its owe side of the Adriatic Sea. Global challenges such as terrorism, the migrant crisis, hybrid wars will be examined in its current form especially from the aspect of the national security. It will provide a foresight on potential threats to the system, as the main aim of this paper. A term of a security will be elaborated, as well as terms of national security and information security, in order to present the VTMIS system as part of the national critical infrastructure and its importance for the national security of the Republic of Croatia. Analysing different subjects, the conclusion can be made that threats are present and they exist, but the biggest concern is the actual possibility of them becoming a reality. There is a need to change the current security concept that now mostly recognizes conventional threats. In order to have a protection that is reciprocal to the threats, a comprehensive approach to the security and protection is needed. That kind of protection will join and synchronize all security elements, as well as educate a wide population in the security and cultural field.