The war in Ukraine, escalating into a full-scale Russian invasion in February 2022, profoundly affects European and global security and shapes public opinion in affected countries, including the Czech Republic. This paper examines the impact of Russian disinformation campaigns on public perception in Czech society, where various narratives influencing attitudes have been circulating since the beginning of the conflict. Some originate domestically; others reflect externally driven disinformation aimed at eroding trust in official institutions and weakening national support for Ukraine. The paper presents evaluations based on quoted references concerning the impact of disinformation narratives on public discourse and the national security of the Czech Republic. The findings highlight risks posed by foreign information influence, underscore the role of media and civil society in countering disinformation, and emphasise the necessity of coherent and effective strategic communication. Building societal resilience through media literacy and critical thinking is essential for mitigating the impact of disinformation and sustaining democratic stability in the face of ongoing geopolitical challenges, particularly by reinforcing public trust in both national and Euro-Atlantic democratic institutions.