Cyberspace has become a key operational domain for modern armed forces, alongside land, sea, air, and space. This article examines how the United States and the Russian Federation conduct military operations in cyberspace, focusing on their official doctrines, organisational structures, and practical capabilities. The analysis highlights fundamental differences in how both countries define cyberspace and use it for offensive, defensive, and strategic purposes. Particular attention is paid to the role of electronic warfare and the integration of cyber capabilities into broader military planning. The article also considers the implications of these differences for NATO and the European Union, especially in the context of growing tensions and the evolving nature of hybrid threats.