The aim of this work is to investigate the impact of information and disinformation on public knowledge and national security in general. With the rapid development of information and communication technologies, the digital information and communication space is also developing which is full of various (dis)information that was (un)intentionally placed there. The work conducts theoretical research based on analysis methods, the inductive-deductive method, the method of description, abstraction and comparison. The space of public knowledge is not filled with true and objective knowledge, namely, more and more such space is filled with various (dis)information with the aim of realizing the interests of individuals or groups. Public knowledge is formed in the public media and is therefore subject to manipulation. The development of technology leads to the emergence of hybrid threats. Hybrid threats are primarily used in the information domain of human life, and they try to influence the information available to the target audience in order to induce them to make decisions in accordance with the attacker's intentions. Hybrid threats are based on influence operations, the most important are information and media operations. The protection of the corpus of public knowledge and the national security of the state is achieved through the adoption and implementation of the national information strategy as well as international cooperation in order to shape public knowledge based on objective, true and verifiable information.